Merge pull request #290 from vishwasbabu/mifosx-223

fixes for accepting user generated payment types
Merge pull request #292 from vishwasbabu/mifosx-223

bug fixes for mapping payment channel to ledger accounts
Merge pull request #293 from vishwasbabu/mifosx-223

ensure payment details are copied over while duplicating transactions
updating api docs with examples of payment channels usage during disbursements and repayments