Allow for success/failure conditions to abort process, fixes #27

Based heavily on code and discussion with @yuchi and his similar
implementation here:
https://github.com/smclab/ti-superagent/blob/f5d1c0e59e57bc1edd3036b7269
a5d58b1d480a7/tasks/titanium.js#L227
new fixture for failure testing
add tests for success/failure testing
move fixture
docs for success/failure options
remove old caveat
remove debug logging
fix test path
refactor killing
fix double callback() bug
testing docs
alloy for various failure/success types, relates to #27
tests for success/failure