pip-compile logs to stdout

[cjerdonek]

pip-compile logs its verbose output to stdout instead of stderr.

Steps to replicate

1. Create a test requirements.in file.
2. Run pip-compile --verbose requirements.in > temp.txt

Expected result

You should see verbose logging in the console.

Actual result

No output is visible in the console.

[nvie]

This is a bug. Thanks for reporting!

[atugushev]

Fixed in #834