close #75
fix typo. closes #75
rename CPLEX
0.2 release changes
use characters instead of symbols for MathProgBase cb functions
support GLPK for callbacks
update docs; CPLEX -> CPLEXLink
fix links
update links to JuliaOpt
mention GLPK for callbacks
formatting fix
Merge pull request #76 from JuliaOpt/zeropointtwo

Prepare for release
typos
expose unbounded/infeasibility rays
fix #79
ref #79
fixup
Merge branch 'master' of github.com:JuliaOpt/JuMP.jl
finally fixes #79
have travis test on both release and nightly