Spring support (fixes #40)

[pgaertig]

No description provided.

[rymai]

Thank you!

[pgaertig]

Important: The spring testunit command of official version 0.0.8 of spring is running only file specified as first argument, other are ignored. With such behaviour guard-test with ':keep_failed => true' which is default will always stick on first failing test and won't run you any other tests. This is most visible when you modify test_helper.rb, which should run all tests but spring runs only the first one specified.

Fortunately this issue has been fixed recently in spring master and all test files given in arguments are invoked, see #102.
However that has not been packaged yet, therefore while waiting for spring 0.0.9 release I recommend to use:

 gem 'spring', :git => 'git://github.com/jonleighton/spring.git'

[rymai]

Thank you! I've updated the README for now.