Ground-up rework of the application

[josecurioso]

This is a huge change in the project (hopefully for the better) so a live deployed version is available here so you can see for yourselves when reviewing the pull request.

Features/changes included in this pull request:

• New GUI using Angular Material and following the Material Design principles for a cleaner UI.
• New models for the various types of notifications.
• New hashing approach for creating new chats and chat folders.
• Added the possibility of creating group chats.
• The application now properly reacts to the LongChat notification and a new notification for DeletedMsg has been included.
• Improved the reaction speed of the app, resulting in less time waiting for the messages to load and an overall better feeling.
• Fixed vulnerabilities that could be fixed from our dependencies.
• Fixed a bunch of Codacy code quality issues.
• Fixed and improved the npm run ghpages:build script which now generates fully working builds.
• Added profile picture to the messages and limited the deletion feature to the messages sent by the logged in user.
• Fixed the tests broken by all of the above.
• Included e2e tests in the Travis build so we get notifications if they fail (e2e tests are however not included in the coverage).

Features/changes not included in this pull request:

• Revise the code documentation and adopt a standard so we can generate HTML files with said documentation.
• We could look into integrating browser notifications in our app so the user gets asked for permission and can opt in for a better experience.
• We should implement snackbars to give feedback in situations like adding friends, creating a new conversation or deleting a message.
• Fixing bugs caused by obscure situations/behaviors that have not been tested.
• Make sure all strings are in english.
• Implement theme-changing which should be easy using Angular Material Themes.

[josecurioso]

The codacy errors missing are minor and we will have to live with them.

[josecurioso]

No luck fixing the errors, I'm merging it to master then.