instructors and past bootcamps cluster refined. Minimum cluster size set to 1, so Instructors and past boot camps always show their symbol. Instructor symbol is person, always shows number. Past bootcamp symbol is light blue circle, shows number until zoom is too large. In this case, the individual symbols become clickable for information.
Merge pull request #168 from BernhardKonrad/master

More google map fixes

- standardize markers
- show more markers on the map when zoomed out