refs #2: now TBTableDataRow's property `enabled` is readonly and setEnabled:withContext: is added.
refs #2: now TBActionRow's property `image` and property `title` are readonly and their setters with context parameter are added.
refs #2: now TBCheckRow's property `title` and property `value` are readonly and their setters with context parameter are added.
refs #2: now TBLabelRow's property `title` and property `detailText` are readonly and their setters with context parameter are added.
refs #2: now TBNavigationRow's property `title` and property `detailText` are readonly and their setters with context parameter are added.

A work in `-[TBSingleChoiceNavigationRow setSelectedIndex:]` is tentative.
It will be fixed in next work on TBSingleChoiceNavigationRow.
refs #2: now TBSingleChoiceSection's property `selectedIndex` is readonly and its setter with context parameter is added.
refs #2: now TBSwitchRow's property `title` and property `value` are readonly and their setters with context parameter are added.
refs #2: now TBTextFieldRow's property `title`, `text`, `placeholder` and `textFieldWidth` are readonly and their setters with context parameter are added.
refs #2: now some TBSingleChoiceNavigationRow's properties are readonly and their setters with context parameter are added.
Merge pull request #4 from hironytic/issue-2

closes #2: each data properties in sections and row now has a setter with a context parameter.