Add post-merge capability to pre-commit-hook.rb

This will make it possible to run a post-merge check when
pre-commit-hook.rb is referenced as a symlink from .git/hooks/post-merge

The kind of check you're going to do is entirely dependant on the
basename of the file, which is a little weird but convenient.

Verification is a little tricky on this. Coming soon.
Remove the broken SPOTCHECK_RECENT stuff
Also remove SPOTCHECK_RECENT from travis.
Add a new .travis.yml
Let's not screw up the .travis.yml
Okay just run it once
Can we test the modules before the bundle install?
Be explicit about which mode we're in.

[SeeRM #8779]
Update the comment docs on pre-commit-hook.rb

[SeeRM #8779]
Fix symlink commands
Land todb-r7#6, fix the comment docs
Land #3188, deluxe msftidy post-merge hook