Paramterize atlassian.product.version

[0x6e6562]

The POM contains these properties which I needed to set in order to get JIRA to run from IntelliJ:

<atlassian.product.version>3.13.4</atlassian.product.version>
<atlassian.product.test-lib.version>3.13.4</atlassian.product.test-lib.version>
<atlassian.product.data.version>3.13.4</atlassian.product.data.version>

This might be an issue for anybody running something other than 3.13.4. Maybe we should think about parameterizing this.

[paulj]

The concern I'd have with parameterizing this is that it potentially de-stabilizes the build. Given that this is Java, compiling against the wrong version is unlikely to be a concern - a non-compatible version of the library would also necessitate a code change.