Use basestring instead of Array in RefData

If multiple files are grouped, use a StructData , with multiple RefData sharing the same types.

Update type/format, to use the FormattedType class
Merge branch 'develop' of https://github.com/mobyle2/mobyle2.lib into develop
fix some issues with refdata vs structdata and adapt tests
InputProgramParagraph inherits InputParagraph
parent term is a reference, not the term itself.
replace calls to mongokit's find_one with fetch_one

find_one *does not* manage inheritance and should not be used.
correctly instanciate ExecutionRule objects.
path property in RefData is now a string, not a list.
correctly set output type
correctly set type properties
add properties such as argpos, format, paramfile to OutputProgramPara*
correct new services import errors raised by mongokit corrections.