webapp: remove unused code
webapp: use #to_json_value to handle floating point fields properly

to_json_value will properly marshal NaN, Infinity and -Infinity as
strings, as JSON cannot represent them and they are important in
our case (the recommended solution of setting them to null won't work
for us)
mention in manifest.xml which gems are needed for the test suite
ruby_tasks: set a model for created permanent ports
test,webapp: make the tests robust against changes in typelib and orogen
fix type used to create port models in #port

We need to use the orocos type name, not the typelib type name,
or we'll try creating ports of intermediate types instead of
opaque types.
webapp: explicitly set to typelib's special float value convertion to :string

Typelib follows the JSON spec now and NaN and Infinity to nil by default,
but that's really not what we need for Rock.