2 commits now in 1 because I forgot to branch earlier.

1. Make RegExp static final.

2. ParameterProviders now only accept the parameter name, the processor
decides on what the name it wants is.
Twitter and dropbox endpoints updated to use the newer way of specifying
default values. 

i.e. from %{name=defaultValue}
to %{name=theName|value=defaultValue}
Merge pull request #677 from fmoloney/FixParameterProviders

Fix parameter providers