Composite methods to explicity create from parts array

Allows new composites to be created without the ambiguity of base initialize.

Composites can be created from an array of parts, followed by the options hash,
similar to the basic initializer, but the new method will not attempt to detect
packed parts as an argument.
Factor out make_from_parts for basic initializer

Use the same code to make parts as when explicitly creating from an array.
Create new composite column in test, not in setup

Need to add the column before inserting.
Remove trailing comma

Fails with ruby 1.8.7
Merge pull request #196 from nearbuy/master

Composite methods to explicity create from parts array