Add packages required to build the library to dependencies

This allows other packages to depend on the ol3 package and get the build tools (devDependencies are not installed when they are transitive dependencies).  The justification here is that the ol3 package becomes useful to other packages when you are able to run the build.js task.  For this task to run all of its dependencies must be available.
For jsdoc to find plugins, we need to set the cwd

This allows the `build.js` (and the exports from `generate-info.js`) to be run with a different working directory.
Merge pull request #2376 from tschaub/transitive

Add packages required by the build task to dependencies.