Correctly support branch names with slashes

Previously, branches with slashes in the name would consume all slashed
segments in a URL, causing the routes to capture incorrect file paths.

This solution is not particularly elegant - anywhere a route used
both a commit-ish identifier and a path, we collapse those two params
into a single param, and parse that param inside the route.

It seems to be working reasonably reliably, but has not seen extensive
testing.

It is also not particularly pretty. If anyone sees ways to improve it,
please, have at it.
Fix minor grammar error in commit views

Use the phrase "authored on <date>" rather than "authored in <date>".
Merge pull request #259 from NateEag/fix-branches-with-slashes

Correctly support branch names with slashes
Merge pull request #257 from NateEag/swap-in-on-commit-view

Fix minor grammar error in commit views