Provide some serialization flexibility for @PathParam, @FormParam, @HeaderParam etc.

[mmazi]

Currently, all parameters are simply toString()ed (except for BigDecimals). Some flexibility should be provided here, eg. for:

• BigDecimals (see also #48) and floats,
• Collections and arrays,
• Dates and times.

Note that this issue doesn't apply to json data since it has its own flexible serialization (by Jackson).

[mmazi]

See how RestEasy, Jersey etc. handle this.

[mmazi]

I think serialization in rescu should generally be refactored (eg. factor out the serialization methods from Params); serialization should be separate from the beans that hold data. This deserves a new issue.