Method to add time to ParametersI

[muhanadz]

Added new addTime() method for omero.sys.ParametersI class. Added tests to test this method.

Without this PR, adding rtime type object required manual mapping:

params = omero.sys.ParametersI()
date = datetime.datetime.fromtimestamp(1)
params.map["Date"] = omero.rtypes.rtime(date)

With this PR, it is possible to add the date directly:

params = omero.sys.ParametersI()
date = datetime.datetime.fromtimestamp(1)
params.addTime("Date", date)

[sbesson]

The API addition looks straightforward and mirrors the existing convenience methods for passing primary types. The change will require a minor release incremental to mark the backwards-compatible API and potentially could go in with #326.

@muhanadz is there a location in the OMERO.py/OMERO.web that could make use of this new API?

[muhanadz]

@sbesson I'm not sure. I simply needed to add time to an HQL query via the ParametersI() model but instead had to manually map the datetime object, since there wasn't a method for that. Added this method in case someone needed this in the future.