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
Adding SkyRectangularAperture and SkyRectangularAnnulus classes
Adding test for SkyRectangular classes