Fixed preloading of modules

[Jontem]

Hi!

This is a PR for #257. I've added a unit test which verifies the solution. Unfortunately the typings for node doesn't contain the definition for _preloadModules so i had to cast to any. Maybe the typings could be added to? I saw that you authored the node typings.

[coveralls]

Coverage increased (+0.2%) to 86.592% when pulling 7ed06f9 on Jontem:preload-modules into b2e6990 on TypeStrong:master.

[coveralls]

Coverage increased (+0.2%) to 86.592% when pulling 7ed06f9 on Jontem:preload-modules into b2e6990 on TypeStrong:master.

[jonaskello]

Seems like there is a problem with node v4. Is there some other method that will work there?

[blakeembrey]

@jonaskello The code is working, it's the test that's failing. tslint does not exist in node_modules at the time of the test. I would try pre-loading something else like typescript. See .travis.yml for the test configuration (note that tslint is explicitly uninstalled and NPM v2 had a nested structure, so no other module would be providing tslint to be required).

[coveralls]

Coverage increased (+0.2%) to 86.592% when pulling 58e2cf4 on Jontem:preload-modules into b2e6990 on TypeStrong:master.

[Jontem]

@blakeembrey i changed the test case to preload typescript instead. Looks good