Catch only exceptions thrown by model[func]() (fix #454 and re #384)

The Deferred is resolved only if model[func]() succeeds.
More can.Observe documentation fixing
Fix to validation documentation
Add signature/description to pluginName
Fix up to can.util documentation issues.
Updated Mustache helper options object documentation
Fix git commit -m #! documentation issue brought up in #462
A few tweaks to the can.Construct documentation based on https://github.com/bitovi/canjs.com/issues/79
Clean up of a leftover sentence from previous commit.
Fix to some old typos in can.Contruct documentation.
Update can.Construct.prototype.init documentation a bit.
Update rest of construct docs, rolls with .extend across the board.
Removing dead code after return statement.
Merge pull request #455 from scorphus/issue-454-canjs-swallowing-errors

Catch only exceptions thrown by model[func]() (fix #454 and re #384)
Merge pull request #465 from bitovi/dead-mustache-code-465

Two return statements in Mustache.getHelper
Update EJS documentation. Clean up some issues and wording.
Update can.Model documentation. Clean up some issues and wording.
Update can.Observe documentation, various fixes. use .extend
Update links in mustache docs.
Update can.Observe.List docs, lots of fixes to links and formatting.