Updated to support Mambu's 3.4 new APIs and enhancements

1. Updated to use 3.4 model jar
Updated target  name to be: Mambu-APIs-Java-3.4-bin.jar

2. Add wrappers for new APIs;
ClientService: UpdateClient
LoanService: Update LoanAccount

SavingsService:
a) Update Savings Account
b) Approve Savings Account
c) Delete Savings  Account
d) Close Savings Account

3. Search service:
Removed offset param. It’s not used in search API.

4. Updated Request Executor:
Added charset=UTF-8 to Json content header.  MBU-4137 is now fixed to
handle UTF-8 in jsons

5. Logger:
Wrapped Logger calls with a check for Logging Level  (e.g
isLoggable(Level.INFO))  for better memory management
Even when info logging is not enabled - Java Logger still creates the
strings needed for the logging. Some of these strings are huge
(especially for image/document API) and this effects memory consumption

6. URLHelper:
Added URL encoding to the URL string (see fixed MBU-4669 Unable to
retrieve objects that have IDs with spaces or UTF 8 characters, via
API,
Also removed no longer needed verification for spaces in IDs (IDs can
have spaces now in API requests)

7. Demo:
Added test methods for new APIs

8. Verified miscellaneous API Issues fixed  in Mambu:
a) MBU-4210  - Address is not returned with a Create Client request.
OK now
b) MBU-4581 User Permissions object is included with getUserDetails.
Verified.
c) Tested Creating Loan account with guarantors and assets: Creation
Ok.  Get LoanDetails doesn’t return guarantor details

9. Added TODOs for fixing some API issues in Mambu.