devDependencies always install

[scothis]

mapbox-gl-js version: 0.26.0

Steps to Trigger Behavior

1. run npm install mapbox-gl@0.26.0

Expected Behavior

No dev dependencies should be installed

Actual Behavior

Dev dependencies are installed

The npm-shrinkwrap.json file includes dev dependencies and take president to the package.json. The common practice is for applications to shrinkwrap their dependencies, but libraries typically should not. As a library, shrinkwrapping dependencies can result in larger downstream bundle sizes, as common libraries are less likely to be dedupped.

[scothis]

The shrinkwarp is also causing npm install failures on travis-ci while compiling the gl module (which is a dev dependency).

> gl@4.0.2 install /home/travis/build/mapbox/studio/node_modules/mapbox-gl/node_modules/gl
> prebuild --install
prebuild WARN install /usr/lib/x86_64-linux-gnu/libstdc++.so.6: version `GLIBCXX_3.4.18' not found (required by /home/travis/build/mapbox/studio/node_modules/mapbox-gl/node_modules/gl/build/Release/webgl.node)
make: Entering directory `/home/travis/build/mapbox/studio/node_modules/mapbox-gl/node_modules/gl/build'
  CXX(target) Release/obj.target/angle_common/angle/src/common/Float16ToFloat32.o
In file included from ../angle/src/common/Float16ToFloat32.cpp:9:0:
../angle/src/common/mathutil.h: In constructor ‘gl::IndexRange::IndexRange()’:
../angle/src/common/mathutil.h:563:20: error: type ‘gl::IndexRange’ is not a direct base of ‘gl::IndexRange’
make: *** [Release/obj.target/angle_common/angle/src/common/Float16ToFloat32.o] Error 1
make: Leaving directory `/home/travis/build/mapbox/studio/node_modules/mapbox-gl/node_modules/gl/build'