initial template definition

add default methods

initial template definition with default methods and interfaces

add design template regions
add proper names and descriptors to definitions
add allowed interfaces to regions definition

add handler test cases, register new definitions

add interface and attribute validation, add test cases for handlers, add test case for template regions

remove template label in test design

rename placeholderText to placeholder
refactor definition maps, fix test cases
refactor handler test cases for designdef
add multiple template validation, test cases
use DefDescriptors instead of SubDefDescriptors for child definitions
Merge branch 'designdef-templates' of git.soma.salesforce.com:ryan-hall/aura into bob/master-pending/pr126-design-templates
Merging origin/bob/master-pending/pr126-design-templates into master