Explicitly check model/variable hygiene
JuMP has been pretty cavalier in tying Variables to Models; this
hopefully fixes that. Variables not owned by a model can be introduced
in the constraints, and printing will not choke on this. However, it
will spit an error when attempting to solve (this is important for
stochastic, where you want to share variables at the modeling---but
not solving---step.
Added sum for JuMPDict
Merge pull request #117 from JuliaOpt/sumop

Added sum for JuMPDict
solution for #118
Support for dot() product
Merge pull request #121 from jlepird/master

Support for dot() product
update NEWS and LICENSE
Merge branch 'master' into nlp