add list FieldMetaType

Conflicts:
	py/nupic/data/fieldmeta.py
init Vector encoder

this encoder takes a list of elements (of same type)
and encodes them.
VectorEncoder: add constructor for OPF version

uses ScalarEncoder and passes all params to it
VectorEncoder: add constructor for SimpleVector - easy to learn
VectorEncoder: add param typeCastFn which casts output from string to type
VectorEncoder add unittests
Vector: decode() output is EncoderResult structure

to fit other Encoders, ...
Vector: add getData() to get data part from decode() result
SimpleVector: make little more customizable
Merge pull request #426 from breznak/vector

Vector encoder, first merge, hope it's ok ;)