Update to comply with current version of otb

Hi Jordi,

I am working on OTBBioVars on behalf of CS Group. I did some modifications on OTBPhenology to make it compatible with the current remote module template : I modified the CMakeLists to be able to compile it out of OTB tree, and I updated parameters description in SigmoFitting.cxx so it is well integrated in the documentation when you compile OTBPhenology within OTB. This merge request will permit to update OTBPhenology git TAG on the next release of OTB to incorporate these changes.

Best Regards, Thibaut ROMAIN