Update to the latest version of closure-compiler

New version v20141120 of closure-compiler are published after my last pull request (see [here](http://mvnrepository.com/artifact/com.google.javascript/closure-compiler/v20141120)). I think that it's better to use the latest version of the closure compiler for the next release of jqGrid.
Merge pull request #659 from OlegKi/master

Update to the latest version of closure-compiler
Publishing jqGrid 4.7
Merge branch 'master' of git@github.com:tonytomov/jqGrid.git
Merge branch 'master' of https://github.com/tonytomov/jqGrid.git