Fixed wrapper to deal with a failed distribution download.
Split up the wrapper int tests and added some coverage for failed dist download.
Moved the check for the wrapper jar size to live in the wrapper int tests. Also fixed the check so that it looks at the correct jar file.
Prefixed field name with '_' to hide it from Groovy.
Include Groovy 2.1.0 in the set we test compilation against.
Tweak to layout.
Some minor spec updates.