Run selected unit/test by test_name - issue #9

[sacre]

for example:

spin push test/unit/account_test.rb:test_sometest

will set -n in ARGV with value regexp '/test_sometest/' before requiring given test files.

also works for many files but not exactly correct:

spin push test/unit/account_test.rb:name1 test/unit/shop_test.rb:name2

is ok, but:

spin push test/unit/account_test.rb:name1 test/unit/shop_test.rb

just run only one test from account_test.rb named "name1"

[jstorimer]

I'm not a fan of the syntax for this because it's so far from what test/unit uses. I'd prefer to go with an approach like #34.

Thanks!