Correct text highlighting for completed tasks

When rangesOfProjects or rangesOfContexts compute the location for
highlighting projects or contexts within a task description, they
always used the task 'text' attribute. However, when a task was
completed there is additional text prepended in the displayed text.
This caused the highlighting to be displayed in the wrong place.

This patch changes the range computation to use the actual displayed
text instead of the 'text' attribute.
Replace RAC with completion blocks for networking
Update unit tests to remove RAC.
Remove RAC from the project

* Remove the submodule
* Remove view/view controller use of RAC, moving TaskCellViewModel
binding logic into TaskCell
Update README to remove RAC notes
Use screen formatted text for calculating cell height
Remove forward declaration of RAC class
Merge pull request #225 from brendonjustin/feature/removeRac

Remove ReactiveCocoa and reimplement affected functionality
Merge pull request #226 from ghewgill/task-cell-height

Use screen formatted text for calculating cell height
Merge pull request #224 from ghewgill/project-highlighting

Correct text highlighting for completed tasks
Updated to latest ActionSheetPicker library
Merge pull request #231 from chuckbjones/230-update-action-picker

Updated to latest ActionSheetPicker library
Migrate from OCUnit to XCTest
Version 1.10