Remove JIRA_ID from RE used to match JIRA Issue

The previous RE seemed to limit JIRA Issue to a particular JIRA project as defined by JIRA_ID.  This is undesirable, particularly where multiple different JIRA projects depend on a common file.
The new RE is also a little simpler, replacing \d\d* with \d+

Thanks for maintaining your fork of git-jira-hook, I found it less buggy than the original by joyjit, although had some trouble installing JIRA REST client in my environment.