(maint) delete a couple unused functions
(SERVER-88) catch errors before they get to Jetty

Add a 'catch-all' middleware to both the Master and CA ring handlers
which catches any Exception, logs it, and returns a simple error message
in the response body.  This prevents Exceptions from propagating all the
way out to Jetty - if this happens, Jetty will generate HTML from the
stacktrace and return this to the client.
(SERVER-88) improve exception handling

* 'wrap-exception-handling' now includes the exception type + message in
  the response body it returns.

* Update the exception handler in the liberator resources to simply
  re-throw exceptions, causing them to be handled in middleware.
(maint) fixup botched merge conflict resolution
fix typo in docstring
Merge pull request #285 from KevinCorcoran/SERVER-88/no-html-in-500s

(SERVER-88) catch errors before they get to Jetty