Gitignore, and shinier "resolveURLTemplates"

Features:
- .gitignore file ignores node_modules and bower_components
- resolveURLTemplates is parameterized, so the macro values are not hard-coded like they are [here](https://github.com/dailymotion/vast-client-js/blob/master/src/util.coffee#L21)
- also adding another macro format, "%%MACRO_NAME%%", because urls may or may not come formatted
- added some test cases, all of which seem to pass