added conversion to SI units from 9ml units
debugged projections.py for new reference resolution
added a test annotation
added annotations to abstraction layer readers and writers
debugged annotation decorator
debugged selection to_xml
Merge pull request #60 from tclose/decorators

Added annotations to (almost) all 9ml elements via decorators
Added some required structures/prototypes to the catlog that I need for the network I am modelling
Added more components to the catalog, required to implement our test
network.
refactored displacement_expression and uniform_probability_region
definitions
refactored regionGreaterThanZero back to just region
refactored all "<component>" and "<parameter>" definitions to match
python nineml loader, which expects "<ComponentClass>" and "<Parameter>"
(could have done this the other way around, but wasn't sure which would
be preferred)
refactored ComponentClass to ComponentClassStub
Converted ComponentClassStub names into valid c-style names
fixed "pertubation" spelling mistake
renamed displacement expression to be more explicit
removed distanceUnit tag from displacement relative expression
removed distanceUnit tag from displacement relative expression and
uniform_probability_connector
minor refactoring
created some more network structure stubs and refactored some parameter
names in the nineml catalog