Issue title: Gio version of the CPU frequency monitoring ready for testing
 Issue body:  Gio version of the CPU frequency monitoring is working faster in 26 to 200 times on my machine.
So there is no GLib.Processing for cpufreqctl, no bash, no cat, no grep each 2 seconds anymore.
 Comments: 
 Comment 0: New branch available here:
https://github.com/konkor/cpufreq/tree/gio
Archive for downloads:
https://github.com/konkor/cpufreq/archive/gio.zip
 Comment 1: Would you like me to benchmark it against my machine?
 Comment 2: Ohh hi) Ofc i'd like it!
 Comment 3: heeey :) alright going to test that!
 Comment 4: To benchmark u can just run 'benchmark.js' from archive folder... Did you have a lags before async calls?
 Comment 5: I was actually going to do that thanks.
Yes, remember, I was the one opening the issue about it.
 Comment 6: Nice. So you can test it for this issue a few days.
I think it's the best method. It's read directly from the kernel MemoryStream at `/sys/devices/system/cpu/cpuX/cpufreq/scaling_cur_freq` and doesn't call external Linux commands and tools like bash, cat, grep. So this method is saving memory, file headers and less code in the extension. Thank you again!
 Comment 7: ![image](https://cloud.githubusercontent.com/assets/12665563/24082929/fc724c22-0ccd-11e7-873c-a3c3d195e127.png)
13 times faster for me!
 Comment 8: That's nice maybe wait some days for more testing but definitely go for Gio!
 Comment 9: For my system (Core i7-920 8 CPU Threads) it's:
```
Gio start...
Gio test end. 94 milliseconds.
GLib processing start...
GLib processing end. 2382 milliseconds.
```
and for 1 core thread simulating it's:
```
Gio start...
Gio test end. 13 milliseconds.
GLib processing start...
GLib processing end. 2340 milliseconds.
```
 Comment 10: I have an AMD FX9370 8 CPU threads

Performance governor (4.4Ghz 8 cores):
```
Gio start...
Gio test end. 454 milliseconds.
GLib processing start...
GLib processing end. 7035 milliseconds.
```

Powersave governor (1.4Ghz 8 cores):
```
Gio start...
Gio test end. 492 milliseconds.
GLib processing start...
GLib processing end. 7030 milliseconds.
```

Performance governor (4.4Ghz single core):

```
Gio start...
Gio test end. 21 milliseconds.
GLib processing start...
GLib processing end. 1936 milliseconds.
```
Powersave governor (1.4Ghz single core):

```
Gio start...
Gio test end. 285 milliseconds.
GLib processing start...
GLib processing end. 17896 milliseconds.
```



 Comment 11: Thank you. I'll push this version to master branch in few days if you or someone other don't report some issues.
 Comment 12: So about ur tests. 17896 ms is too much!!! About 18 seconds!!! I think ur HDD has issues. 
 Comment 13: Here is my test for example
powersafe (1.6GHz)
```
Gio start...
Gio test end. 150 milliseconds.
GLib processing start...
GLib processing end. 2419 milliseconds.
```
performance (2.67GHz)
```
Gio start...
Gio test end. 94 milliseconds.
GLib processing start...
GLib processing end. 1758 milliseconds.
```
 Comment 14: Why would this relate to HDD? The whole system was laggy and I guess it's what you expect from a 1.4Ghz single core cpu running a high demanding desktop environment. 
 Comment 15: terencode maybe u are right. i'm just talking about checking HDD's smartdata.
 Comment 16: OMG now benchmark's results looks like:
(100 cycles)
```
Gio start...
Gio test end in 0 milliseconds.
GLib processing start...
GLib processing end in 2150 milliseconds.
```
for NUMBER_OF_TEST_CYCLESx10 (1000 cycles)
```
Gio start...
Gio test end in 4 milliseconds.
GLib processing start...
GLib processing end in 21777 milliseconds.
```
It's like nothing now! 5500x FASTER then old GLib.method!
 Comment 17: Thanks for caring for my HDD health but it's doing alright (S.M.A.R.T  ok). ;)
 Comment 18: I can't see any problems to merge this version to master...
 Comment 19: @konkor you can close this now :)
 Comment 20: OK, GIO version (v9) is in extensions.gnome.org and merged to master. So it's look like closed.
{'source': 'GithubIssues', 'repo_name_with_owner': 'konkor/cpufreq', 'issue_id': 215275493, 'repo_stars': 503.0}