ERXExistsQualifier Improvements

Various improvements to ERXExistsQualifier including the ability to make it produce an "in" clause instead of an "exists" clause. The ability to pass a long keyPath into the Qualifier. Fixed various bugs in string replacements with complex joins and also issues noticed in Postgres string replacement of “int4” and “int8"

This is a re-submission of pull request #525 because somehow I had made a branch on WOCommunity and the pull request was tied to that. I've deleted that branch and I am resubmitting the request from the correct repos.