limit the number of files to be included in the build

[mef]

This is a proposal to fix #1541.

Changes:

• Move all dependencies to devDependencies instead of dependencies, so that they are not included when running npm install intl-tel-input.
• Only include the build and the documentation inside the npm package.

This dramatically decreases the package size, making it faster to install, and consuming 100x less disk space (1.2MB instead of 122 MB).

[jackocnr]

Thanks very much for this. I've merged the commit manually and added a further commit with some fixes. I'm just waiting for Travis to fix my testing account to check all ok there, and then I will do a new release including this. Thanks again.