Alpha 1 release for 1.2.0 for Confluence 5.9

This is a preliminary release for users who need this plugin now but can't wait for a release.

There are known issues with this release

• For each deletion an exception is written to the log, this is caused by CONF-36714
• Attachment deletions are taking significantly longer than they used to, in my tests this is resulting in around 1 second for each file. Thus if 10,000 attachments are being deleted in one run (not uncommon) it's likely to take 3 hours. For the criteria needed a test server here has been taking 8 hours which has not had attachments purged for the past year. Potentially caused by CONF-40630 though I actually think this is a larger issue that Atlassian are not yet aware of as this issue was supposed to be resolved in 5.9.5.

As a workaround for the above I have introduced a new configurable option for the system settings which allows you to limit the maximum amount of deletions per pass. While this doesn't eliminate the issues it may help you manage them. It's also neat for testing too.

I advise adding "com.drunkendev" to the logging options and setting it's level to DEBUG which will provide more detail in the logs as to what it's actually doing.

A little extra debugging detail is now appended to the email which is mainly for my own tests to see what the timings are like on a confluence instance with thousands of attachments rather than trying to metric my debugging session.

As Confluence 5.9.* now requires Java 8 the plugin has been updated to take advantage of this where possible.