Run `lint` in commit hooks. (#5666)
Run `lint` in commit hooks. (#5666)

### Problem

The third travis shard runs `./pants lint`, and frequently fails with trivial errors like unused imports.

### Solution

Add `./pants --changed-parent=master lint` to the pre-commit hooks.
pantsbuild/pants,pantsbuild/pants,UnrememberMe/pants,benjyw/pants,jsirois/pants,pantsbuild/pants,UnrememberMe/pants,twitter/pants,baroquebobcat/pants,tdyas/pants,tdyas/pants,twitter/pants,foursquare/pants,twitter/pants,pantsbuild/pants,tdyas/pants,baroquebobcat/pants,wisechengyi/pants,foursquare/pants,wisechengyi/pants,tdyas/pants,jsirois/pants,foursquare/pants,UnrememberMe/pants,jsirois/pants,twitter/pants,tdyas/pants,twitter/pants,baroquebobcat/pants,UnrememberMe/pants,foursquare/pants,pantsbuild/pants,benjyw/pants,foursquare/pants,baroquebobcat/pants,wisechengyi/pants,tdyas/pants,wisechengyi/pants,twitter/pants,benjyw/pants,UnrememberMe/pants,baroquebobcat/pants,tdyas/pants,tdyas/pants,tdyas/pants,foursquare/pants,UnrememberMe/pants,baroquebobcat/pants,pantsbuild/pants,benjyw/pants,twitter/pants,foursquare/pants,baroquebobcat/pants,benjyw/pants,wisechengyi/pants,benjyw/pants,benjyw/pants,UnrememberMe/pants,wisechengyi/pants,twitter/pants,wisechengyi/pants,pantsbuild/pants,baroquebobcat/pants,UnrememberMe/pants,UnrememberMe/pants,foursquare/pants,twitter/pants,wisechengyi/pants,wisechengyi/pants,baroquebobcat/pants,foursquare/pants