Added methods to change context

Added

• Added comments to config file;
• Added timely_app_t *current_app pointer to store the opened app;
• Added methods to change context;
• Added style to watchface fonts;
• Added functions to manage the applications;

Fixed

• Fixed typo in weather app;

Changed

• Changed weather stock application by adding name and description labels;
• Renamed timely_main to timely_watchface;
• Renamed timely_setup to timely_launcher;

Removed

• Removed unused event handler function;