fix(build): Use "umd" as library target for libraries

[nanovazquez]

Today when installing the packages in a web app, we are getting this error:

This could be caused by multiple reasons, and sadly we cannot reproduce it locally through npm link. This PR tries to fix the issue by:

• Replacing the libraryTarget from commonjs2 to umd, as commonjs uses require() to load dependencies.
• Force the target to web (although web is the default value). This is to let Webpack know that the environment is a browser and thus, the require() function is not available.