Removing TaskType in favor of group

[scalvert]

This removes the TaskType enum and type prop in TaskClassification in favor of a group string prop. This provides more flexibility to specify both the category (primary grouping mechanism) and group (secondary grouping mechanism).

Example: under the linting category, you could specify an eslint group comprised of 3 tasks and a template lint group comprised of 2 tasks. The sorting would be as follows:

linting

eslint task 1
eslint task 2
eslint task 3

template lint task 1
template lint task 2 

TODO

• Add sorting secondarily by group (after category)