gem build prep
update license and version
update gemspec and readme
use more helpful template
generalize usage
Merge branch 'master' of https://github.com/colinrymer/guard-shotgun

Merging an useful fork.

Conflicts:
	.gitignore
	Gemfile
	guard-shotgun.gemspec
	lib/guard/shotgun.rb
	lib/guard/shotgun/version.rb
Updates after fork merge