use minitest & its assertions
use exit! rather than exit in file_writeable?

We don't want to invoke the at_exit hooks setup for tests
- they cause an exit status of 1 even if the file is writable
run against 2.0.0 and 2.1.0
run against 2.1.5 rather than 2.1.0
test_watch.rb will fail if there are fake triggers that are left registered
initialising slashprocprofiler causes a failure (because it does an unexpected File#read)
this spec was failing intermittently - from calls to wait on other ConditionVariable instances
constrain to a version of moustache that still supports 1.8.7
fix fetch_system_poller stubbing
Merge pull request #205 from fcheung/make_tests_green_on_20

Make tests green on 20
Use simplecov instead of rcov.
Supports ruby 2, in addition to 1.9.3 and 1.8.7
Set ENV['COVERAGE'] from the :coverage task, for backwards
compatibility, though preferred way to run this would just be
`COVERAGE=true bundle exec rake test`.