Add options to customize Redmine URL, Redmine date format

I found that I couldn't get this working without modifying the date format to match what my Redmine instance served, and couldn't get the subset of issues I wanted synced without feeding in a specific URL.

This commits in this pull request create options for date format and Redmine issues URL while retaining the old values as defaults.

It also includes a .gitignore that prevents tracking of Python build artifacts.