Update CHANGELOG.md
just fixing typo skd_config.properties -> sdk_config.properties
Merge pull request #20 from yusuke/master

just fixing typo skd_config.properties -> sdk_config.properties
fix encoding problem with IPN Messages
Fixing credentials logging and removing random seed.
Merge pull request #21 from uwemaurer/master

fix encoding problem with IPN Messages
Merge pull request #23 from paypal/bugfixes

Fixing credentials logging and removing random seed.
Update core version in pom.xml to 1.5.1
Merge branch 'master' into stable

Updating core version in pom.xml