Updating ClosureCompiler to support option banners.

When compressing production code it is often important (or legally required) to add in a copyright or attribution notice. This allows one to be easily set in a compatible way with many other grunt plugins - using a banner variable in the options.
removing needless additional setting of banner option
Updating ClosureCompiler to support option banners.

When compressing production code it is often important (or legally required) to add in a copyright or attribution notice. This allows one to be easily set in a compatible way with many other grunt plugins - using a banner variable in the options.
Merge branch 'master' of github.com:abritinthebay/grunt-closurecompiler
Merge pull request #6 from abritinthebay/master

Updating ClosureCompiler to support option banners.