Make goblet work in URL subpaths

It is now possible to run it as e.g. http://example.com/goblet/ instead
of needing it to be installed at the URL root.
Always use matching scheme to access fonts

If goblet is accessed over SSL, fetching fonts without SSL triggers an
SSL warning.
Always use flask.sendfile for cache files

Exposing repository files directly seems problematic. This will still
use X-Sendfile when enabled to allow good speed.
Use matching URL scheme to fetch gravatars
Work around potential divide-by-zero error

Under some circumstances, a file will be listed as having no additions
or deletions. This is probably a bug with pygit2, and this commit should
work around that issue.
Enable searching anywhere in branch name

This is in contrast to just at the beginning
Enable searches on the commit page

This could be resolved by redirecting to the tree search results page
instead, which might be a better approach.
Add commit hash to commit view

Also improve CSS to format parent commit hashes more nicely.
Go back to the correct tree from the commit list
Fix branch switching in the commits list

The correct way to fix this may instead be to change the name of the
ref_commits view to commits, and rename commits to something else, or
else remove that view altogether.
Fix regex to filter svn info from messages

This regex which is likely there to remove svn information from git
messages is too general and matches things it shouldn't. This is a tiny
tweak to make it behave better, but it likely needs to be completely
redone to be much more narrow.