Update CHANGELOG.md

for 1.19.0 release
Update CHANGELOG.md
adding category for newly added savings reports
MIFOSX-954 - added update of default savings
adding missing property to clientSavingsSummar
updates for 1.19.0 release
MIFOSX-948 Added UGD links to API DOCS
Merge pull request #790 from pawandubey/api-doc

MIFOSX-948 Added UGD links to API DOCS
Merge pull request #788 from pramodn02/MIFOSX-954

MIFOSX-954 - added update of default savings
added savings test cases
Merge pull request #791 from pramodn02/savings_test

added savings test cases
test case corrections
Merge pull request #793 from pramodn02/savings_test

test case corrections
 MIFOSX-980 - added boolean flag for first repayment date caculation
MIFOSX-945 - added null check for id while sorting the transactions
MIFOSX-216 - added grace before In Arrears
MIFOSX-975 - added Arrears status
Merge pull request #797 from pramodn02/MIFOSX-975

MIFOSX-975 - added Arrears status
Merge pull request #794 from pramodn02/MIFOSX-980

 MIFOSX-980 - added boolean flag for first repayment date caculation
Merge pull request #795 from pramodn02/MIFOSX-945

MIFOSX-945 - added null check for id while sorting the transactions