Add Gist code search (#194)

internal/i18n/locales/en-US.yml

@@ -68,6 +68,14 @@ gist.list.files: files
 gist.list.last-active: Last active
 gist.list.no-gists: No gists
 
+gist.search.found: gists found
+gist.search.no-results: No gists found
+gist.search.help.user: gists created by user
+gist.search.help.title: gists with given title
+gist.search.help.filename: gists having files with given name
+gist.search.help.extension: gists having files with given extension
+gist.search.help.language: gists having files with given language
+
 gist.forks: Forks
 gist.forks.view: View fork
 gist.forks.no: No public forks
@@ -164,6 +172,7 @@ admin.actions.sync-db: Synchronize gists from database
 admin.actions.git-gc: Garbage collect all git repositories
 admin.actions.sync-previews: Synchronize all gists previews
 admin.actions.reset-hooks: Reset Git server hooks for all repositories
+admin.actions.index-gists: Index all gists
 admin.id: ID
 admin.user: User
 admin.delete: Delete