remove redundant empty line
Add `rake test`

Tested with:
 * ruby 1.8.7 (2012-02-08 patchlevel 358) [universal-darwin12.0]
 * ruby 1.9.3p286 (2012-10-12 revision 37165) [x86_64-darwin12.2.1]
 * ruby 2.0.0p247 (2013-06-27 revision 41674) [x86_64-darwin12.4.0]
 * ruby 2.1.0dev (2013-09-22 trunk 43011) [x86_64-darwin12.5.0]
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