Use a custom gollum with Thin server to improve performance

This makes it easier to tell when gollum is or isn't available
(I can properly track the pid using a file), reduces the gollum
start up time (by a factor of 10), and slightly improves the time
taken for translating mark-up to HTML (mainly because the HTTP
requests return slightly faster).
Merge pull request #142 from crosswalk-project/gollum-improvements

Use a custom gollum with Thin server to improve performance