ENH: df.to_csv() and pd.read_csv() defaults do not give back original data
#### Is your feature request related to a problem?

I expect when loading and saving CSV data that whatever defaults used for loading and saving can be used mindlessly if my data is simple enough. For example, in the below example, I would expect that ``new_df`` is equal to ``df``:

```
df = pd.DataFrame({'time (ms)': [1, 2, 3, 4]})
df.to_csv('test.csv')
new_df = pd.read_csv('test.csv')
```
However, this is not so. The index is saved as the first column by default, but is not *read* as the first column by default when loading data with ``read_csv()``. 

#### Describe the solution you'd like

I should not have to pass in additional arguments to get the simplest use case to work for loading and saving data. I suggest either not saving the index by default when converting to CSV (this seems less desirable), or setting the ``index_col=0`` by default when loading a CSV file.

#### API breaking implications

``index_col`` would be set by default 

#### Describe alternatives you've considered

Manually avoiding saving the index, and manually adding the ``index_col=0`` keyword argument when loading CSV data. Both have caused me endless frustration.

