Add tags to task

[Raphtor]

Add searchable tags to task schema. Two ways of doing this:

Relational database

Basically, two new schemas Tags and TagDefinitions would be added. Tags would relate tag ids to task ids. TagDefintions would store the definitions to task ids.

Pros:

• Easy updating of tag definitions
• Fastest querying

Cons:

• Extra database, might get big depending on number of tasks/tags

Add tags key in task schema

Just add an array to the task schema

Pros:

• Easy updating of tag definitions
• Fast querying

Cons:

• Can't update/delete tags very easily
• Can't see all tags very easily