Shared libraries are not stripped in the manylinux1 wheels
In all yet uploaded Pandas versions for `manylinux1`, the shared libraries are not stripped and thus ship a lot of bytes overhead.

```
# du -sh /opt/_internal/cpython-3.5.4/lib/python3.5/site-packages/pandas/_libs/
70M	/opt/_internal/cpython-3.5.4/lib/python3.5/site-packages/pandas/_libs/
```

Calling `strip` on these saves 53MiB of space.

```
# strip /opt/_internal/cpython-3.5.4/lib/python3.5/site-packages/pandas/_libs/*.so
# du -sh /opt/_internal/cpython-3.5.4/lib/python3.5/site-packages/pandas/_libs/
17M	/opt/_internal/cpython-3.5.4/lib/python3.5/site-packages/pandas/_libs/
```

If someone could point me to the official scripts that generate these wheels, I would volunteer to change the build process that we only include stripped binaries.