Create a comprehensive dev environment

[teles]

Actually is hard to new developers to contribute to the project because there is no indication of how to build it. So this issue is to create some stuff to make developers life easier as:

• Create a sample index.html using release files;
• Create gulp tasks to watch file changes and update index.html;
• Create a javascript map file for main frontpress.js file (nice to have);
• Create a CONTRIBUTING.md to this project #54 ;

[teles]

I'm working on it. At this moment it's easier to run the project just by using the command:

npm run dev

Now we just have to create javascript map files to have this issue closed.