Fix up issue key matching in plugins

Various plugins (eg. Perforce, Subversion) reply on issue key matching. By default, JIRA ignores keys that are part of URLs. This is a problem with svn/p4 plugins (see the p4 bug, svn bug), where people frequently do enter the URL instead of the key.

As a workaround, we implemented a 'jira.option.ignore.url.with.key' property in jira-application.properties. If set to false, JIRA will not ignore keys in URLs. This is a workaround (undocumented at that), not a proper solution.

We need to work out a) what's wrong with just allowing keys in URLs, b) if there is a legitimate reason for not wanting that, implement a different algorithm for use in Subversion and Perforce plugins.