[865] Add dalli (memcached) configuration.
[865] Add cache_digests to Gemfile for caching.

* Allow cache_digests to track dependencies through haml.
White space.
[865] Opportunity Layout Fragment Caching

* Opportunity layout does a bit of processing and rarely changes for a conversation so let's cache it.
[865] Add fragment caching to conversation show page.

* Convert Conversation Show haml to erb so cache_digests works properly.
* Place sections of view code into haml partials
* cache contents around haml partials in conversation/show page
* Page should expire properly (via using new memcache key) when major changes are made.
* Does not catch minor changes like profile picture changes.
* Let regular cache expiration handle it or add in future touch when user is updated.
[865] Opportunity Layout caching.
[865] Add Managed Issue Page Frament Caching.  Large Fragments.
[865] Allow Annonymous User Type for Cached Data.
White space.
[869] Ability to Receive a Notification of a Comment on a Reflection
[870] Update copy for Welcome Email.
[865] Configuration of Environments for memcached