Change 'this' with $state in $state.go

Allow partial application of $state.go as in _.partial($state.go, ...)
Update README.md

Add npm install instructions
Restore comment in .run function call

In a previous version there was a example of how to use the $state inside a ng-class.
chore(changelog): fix changelog is just plain wrong, was showing features that aren't even released yet.
chore(changelog): fix changelog dates
Added new resource links to videos and ui-router-extras
Merge pull request #1177 from sroe/patch-1

chore(sample): Restore comment in .run function call
Merge pull request #1173 from NickHeiner/patch-1

Update README.md
Merge pull request #1156 from miguelsm/master

chore(style): Change 'this' with $state in $state.go
Linked example titles to plunkrs
fix(docs): Explain return value of rule as function
Merge branch 'master' of https://github.com/angular-ui/ui-router