Fixes#264
Implement the equivalent of java's String.hashCode on the conversation model.
Change avatar template and attributes. Use css classes for colors.
Clicking on a key conflict message opens the message detail view,
which displays the contact(s) in this conversation. If the message
contains a key conflict with any of these contacts, a button is
displayed which attempts to resolve that conflict and any other
conflicts in the conversation that are related to that contact.
Define a Whisper.View base class that automatically parses and renders
templates and attributes defined by the subclass. This saves us a good
number of lines of code as well as some marginal memory overhead, since
we are no longer saving per-instance copies of template strings.
