removed references to only needing Boost.Math and Boost.Python in INSTALL
(#426)
Revert "removed references to only needing Boost.Math and Boost.Python in INSTALL"

This reverts commit 3e05da6c2c38c9ec4057ac9546c68d76904d4c13.
made more minor edits to INSTALL.md to reflect use of Boost.Math
(#426)
minor typo edit
(#426)
merged master into this branch
(#426)
Minor edits to Solve comments
(#426)
Merge pull request #433 from GalSim-developers/#426

#426 Improve behavior of Sersic class
Merge branch 'master' into #343