Update for JuMP v0.18 on julia 1.0 (#82)

* update for julia 1.0

* update travis script

* add LinearAlgebra to REQUIRE

* some updates

* more changes

* add constructors

* define constructor for numbers too

* don't broadcast over norm expressions

* revert to map

* switch back to working version of GLPK

* comment out flakey test for now

it is correct, but the GLPK solver has been problematic on it. see
* #74 (comment)
and
*
8327d3648b0aa59f5355
f9bd56b65e8dda6fa642
for workarounds in the past.

* test on different versions of julia

Merge pull request #71 from IainNZ/require2

change upperbound to jump 0.15

JuMPeR v0.4.0 [abcf0a6]

JuMPeR v0.3.1 [c3524f8]

JuMPeR v0.3.0 [7865011]

JuMPeR v0.2.1 [298588a]

JuMPeR v0.2.0 [3885989]

JuMPeR v0.1.2 [5c9977b]

JuMPeR v0.1.1 [f0580c0]

JuMPeR v0.1.0 [aa60bb4]