Temp workaround for invalid certificate issue on travis-ci
Merge pull request #202 from cdeil/issue-202

Travis-CI failure due to invalid certificate?
Fix exact elliptical overlap issue
Fix a second bug in the elliptical overlap calculation
Merge pull request #198 from cdeil/issue-198

Bug in exact elliptical photometry
Restructured main doc page
Minor doc changes
Add new overview page
Add new installation page
Add new getting started page
Add new background page
Remove width/height attributes for banner logo
Put user doc link directly in main doc page
Add in-development API note
Centralize dependency warnings
Add PSF Reference/API
consistent doc indentation [skip ci]
Update main doc page [skip ci]
datasets docs
Add background docs