update Julia nightly download location
Merge pull request #186 from tkelman/patch-1

update Julia nightly download location
New style sudoku
loosen tolerances. fixes #182
fix check for GLPK, ref #182
avoid Pkg.installed because it's slow
MathProgBase.MissingSolver no longer defined
fix ArrayViews test
fix for change in ReverseDiffSparse
prep for 0.5.3