Added gemspec to use on rubygems.org or with Bundler

- also moved version number to central location
renamed files and gem to conform to radiant’s naming convention
added ruby 1.9 magic encoding comments
Merge branch 'ruby1.9-magic-comments' into gerrit

* ruby1.9-magic-comments:
  added ruby 1.9 magic encoding comments
encoding comment for new file
released new gem version
Merge branch 'gerrit' of git://github.com/gerrit/radiant-exception_notification-extension into 0.8

Conflicts:
	lib/radiant-exception_notification-extension.rb