Product Mix Functionality

Updating Api Docs
Merge branch 'MIFOSX-478' of git://github.com/mifoscontributer/mifosx into mifoscontributer-MIFOSX-478
incrementing version number of product mix db patch
Merge pull request #464 from vishwasbabu/mifoscontributer-MIFOSX-478

Mifoscontributer mifosx 478