Work on form creation.

The linguistics metadata model is now created dynamically from a config
file.
Added doc comment on create_metadata_class.
Added ecology metadata.
Hide class generation.

Metadata class generation is now down in __init__.py.
Metadata handling more dynamic.

Should now be able to define new metadata classes by just putting them
in the metadata folder.
Domain files for metadata.

This should have been in previous commit...
Merge branch 'domain_models' into demo

Conflicts:
	simplestore/etc/templates/simplestore-addmeta.html
Fix missed text from merge.
Handle icons dynamically.