Improved documentation for _.find()

Added the specification of what happens if the no element passes the test.
Expanded testing of _.escape() and _.unescape() to cover all conditions
added unit test for _.where with parameter 'first'
Merge pull request #1120 from qivhou/master

Added unit test for _.where with parameter 'first'
modify _.max function, _.max function now return the first max element of the list instead of the last one if more than one max element exists.
Merge pull request #1124 from liuyl/master

trivial modification on _.max function
shortcircuit nativeBind evaluation
Merge pull request #1127 from vhmth/bindShortCircuit

shortcircuit nativeBind evaluation
Fixes #1122 -- don't clearTimeout(undefined)
fixes #1111 -- docco
Fixes #1102 -- docco
Merge pull request #1093 from rossille/patch-1

Improved documentation for _.find()
Add support for source map

Update the Rakefile so when rake build is done, the source map config file
is generated (by uglify-js) along with the minified source.

Largely inspired by backbone/Rakefile.
Merge pull request #1135 from frediana/master

support for source map
Fix #1141 - Update _.bindAll docs.
Merge pull request #1142 from braddunbar/bindAll-docs

Fix #1141 - Update _.bindAll docs.