Move to Project.toml and fix ImageCore version conflict

• Move to Project.toml
• Update Travis to Project.toml format
• Fix ImageCore version conflict

Add missing package to test file

Merge pull request #136 from RalphAS/ras/imageshow1

switch to registered ImageShow for tests

fix windows

Merge pull request #132 from JuliaIO/sd/wzip

fix zlib build on windows

drop Julia 0.6, support 0.7!

Merge pull request #129 from JuliaIO/fbot/deps

Fix deprecations

metadata

Change package from imagemagick to libmagick6 (#119)

This package requires /usr/lib/libMagickWand-6*.so, which is found in the
libmagick6 package on Arch Linux, not the imagemagick package.  Since
imagemagick has reached version 7, pacman will install libmagick version 7,
which is incompatible with this package.

v0.5.1: Merge pull request #114 from JuliaIO/sd/fixcc

call initenv in deps.jl to work with compilecache=no

v0.5.0: Merge pull request #104 from JuliaIO/fbot/deps

Fix deprecations

More robust installation

Merge pull request #93 from musm/fx

More resilient precompiled builds

v0.3.1: Merge pull request #91 from oschulz/issue-12-refix

Re-fixes issue #12, reintroduced due to 286138d

Fixes for OSX/Homebrew

v0.3.0

README: mention install "reset" for Homebrew users