Updated to support Mambu v3.5 API changes

. Undo Approve API: added for Loan Accounts
2. Undo Approve API : added for Savings Accounts
3. Activities API: Added new Service and new Demo program for
Activities API
4. Added Delete wrapper for Loan Accounts (was missing)

5. Updated build files (pom.xml) to build v3.5-bin version
(Mambu-APIs-Java-3.5-bin.jar). Updated Readme file.
Updated to support Mambu v3.5  (with review comments)
Removed submitting local mambu model jars in libs
Merge https://github.com/mambu-gmbh/Mambu-APIs-Java
Reverted lib files mode of access to the original from the master branch (644)
Merge pull request #27 from mdanilkis/master

Updated to support Mambu v3.5 API changes
- Undo Approve API: added for Loan Accounts
- Undo Approve API : added for Savings Accounts
- Activities API: Added new Service and new Demo program for Activities API
- Added Delete wrapper for Loan Accounts (was missing)
- Updated build files (pom.xml) to build v3.5-bin version
(Mambu-APIs-Java-3.5-bin.jar)
- Updated Readme file.