Add IDEA files to .gitignore
Update Jenkins version and add Mustache in POM

Updated to use Jenkins 1.500 and added the Java implementation
of Mustache from https://github.com/spullara/mustache.java
Use Mustache templates to generate notifications

The plugin will now use Mustache template from configuration when
creating HipChat notifications. This allows you to use any values
available in the build / project configuration, including your own
custom parameters.
Update version to 0.1.3
Add link to completed message
Update plugin version past what's on the plugin repo
Update README with info about using Mustache
Fix empty message issues

When there is no config set there was an empty message being sent,
instead make sure the defaults are used.
Update README with custom var info
Remove MessageBuilder

MessageBuilder is no longer required since we now generate messages
using Mustache.
Make sure "Cause" is available to Mustache

And some minor fixes to ensure there's no doubling up of "Started"
text.
Fix notifier so that is uses job properties

Previous code was incorrectly getting message templates from
the global notifier instead of using the JobProperties object
Simplify the "started" template

Use a single "trigger" string that's the same as the non-Mustache
version's string instead of separate cause & changes strings which
could cause duplications.
Clean up config panels and add help files
Readme update
Fix README indentation
Merge branch 'feature-mustache-messages' of https://github.com/marcins/jenkins-hipchat-plugin into feature-mustache-messages
Update default completion msg to allow html

If the build fails then the completion message may
contain HTML. This means the default message needs to
triple 'stache "status" so that the correct output is generated.
Use StringBuilder properly in getOpenLink

Inefficient use of concatenated strings with String builder when creating the link to the build job.
Use StringUtils to check for blank strings

Style fix to check for blank strings based on feedback.