fixes to files and one addition to troubleshooting

Change list - Zachary was going to check this for me before they were merged:

1. customize/custom-domain-names.markdown and ssl.markdown: made the lines stating that the custom domain and custom SSL are only for PAID accounts bold (I think?)

2. changed getting-started/index.markdown:  link for signups went to login page which tells them to contact support... I changed it just to have them contact support

3. roadmap.markdown: Added a bit after the completed (text that had strikeout) "-- Done!" after each of them as people don't get what the dashed lines are (you have no idea how many thought that meant we weren't doing it!)

4. troubleshooting.markdown: added an issue that a LOT of people have been having related to something going on over at rubygems.org -- now we can just link to it instead of sending them that text.