Fix UNKNOWN output for nagios_check >= 0.1.1

dbroeglin/nagios_check@24aab628b3df52eaa4da26eb30703f850c0b060b changed the
output of UNKNOWN errors to include the name of the exception class. Make
this optional for backwards compatibility.
Fix tests for store_message() output

Commit 9a3b411d4eb1af866f68529b303d2bb745f3e0a9 added a call to
`store_message` which changes the STDOUT to include a string that is
presented to humans, along with the machine parseable information that comes
after the pipe. Account for this in existing tests.
Setup Travis CI

Add metadata and default rake task for Travis CI. This will make future test
failures more apparent to contributors. Will need to be enabled in the
parent repo and any forks.
Merge pull request #5 from dcarley/tests

Fix tests and enable Travis CI
Update README.md
Extend test coverage

Test the arguments `-w`, `--dropfirst`, `--droplast`, and a combination of
both. Uses a larger dataset to distinguish from the different cases. Also
includes a test for null values which aren't considered in the averaged
result.
Refactor data manipulation

Make the code more Rubyesque. Should read better, IMO.
Catch empty responses from Graphite

If a metric/query doesn't exist in Graphite then an empty array will be
returned. Previously this resulted in the exception being returned:

    NoMethodError: undefined method `[]' for nil:NilClass

Replace this with a more user friendly error to indicate that no data has
been returned. This isn't quite the same as not having any valid datapoints,
after dropfirst/droplast.
Merge pull request #6 from dcarley/catch_unknown_metrics

Catch unknown metrics
bump
Include reference to the threshold format

I think it would be useful to include a reference to how the thresholds are formatted to save time when trying to understand what you can do with them.
Merge pull request #7 from tombooth/patch-1

Include reference to the threshold format
Support HTTPS graphite hosts
Merge pull request #8 from ktheory/https

Support HTTPS graphite hosts