Implement initial support of projects

[art-in]

For now, let's implement quick task for supporting projects in following way:

• there's is static list of projects (not accessible for editing);
• to assign new task to project add corresponding tag inside description (like, "[c] This is common task")
  Tag should look like letter inside brackets. Tag can be put in any place of description.
• visually task should indicate its assignment to project by corresponding background.

Tag - Project - Background Color:
[com] (default) - Common needs (buy vitamins, make cleanup in the apartment, etc.) - blue (#C4F2EA)
[c] - Work & Craft & Technology (investigate some js technique, implement some feature) - orange (#FFE1B7)
[s] - Sports & Health - green (#C1F2C1)

[art-in]

Added projectAssignment knockout binding that sets background color, depending on what project tag is in the description.