add designdef getter within component def and fix readonly and required attributes on design defs
modify boolean getters on attribute design def
remove boolean object logic from attribute design def
add placeholder text and description attributes to attribute design def
javadoc for design attribute
move design def descriptor getter to base component def
remove quickfixexception from method signature
update javadoc for AttributeDesignDef
add label attribute to design def
add a few test cases
Merge branch 'designdef-getter' of git.soma.salesforce.com:ryan-hall/aura into bob/master-pending/pr-117-designDef-getter

@P4CL:9331700@
Merging origin/bob/master-pending/pr-117-designDef-getter into master