Fix default useDoubleNumbers for Gradle plugin

This property should be `true` to maintain existing behaviour, and
behaviour similar to all the other plugins/interfaces.

Closes #141.
Move attach-javadocs & attach-sources into release profile
Return the top-most generated JType from SchemaMapper#generate

Closes #137.
Move from commons-lang to commons-lang3
Add useCommonsLang3 config option

Setting useCommonsLang3 to `true` will cause the plugin to use the
apache commons-lang 3.x imports intead of commons-lang 2.x imports when
adding equals, hashCode and toString methods.

Closes #140.
Fix sourceType setting in Gradle plugin

Closes #144.
Add support for generic type arguments in javaType

Closes #151.
Add some more irregular cases to the Inflector
Rename FileCodeWriter to avoid shadowing parent
Add findbugs ignore for exceptional return value of File#delete()
Fix classpath null check in the Ant task
Fix or supress some PMD warnings (Useless parens, unused params, etc)
Allow array properties to have a null default value

Closes #156.
Add @Valid on all collections, not just those with items type "object"

Closes #158.
Use a LinkedHashSet rather than a HashSet for uniqe lists to preserve order
Merge pull request #160 from cmaron/master

Use a LinkedHashSet rather than a HashSet for uniqe lists to preserve order

Closes #159.