Update Adjustments label resource

Signed-off-by: Pierre-Alexandre Meyer <pierre@mouraf.org>
Add ajustments management (cherry picked from commit 098955d7c93e3bb24678914de0f7a598a0bc8dea)

Conflicts:
	src/main/java/com/ning/billing/recurly/RecurlyClient.java
	src/main/java/com/ning/billing/recurly/model/Adjustments.java

Signed-off-by: Pierre-Alexandre Meyer <pierre@mouraf.org>
CREDITS: add entry for ps-ngr

Thanks!

Signed-off-by: Pierre-Alexandre Meyer <pierre@mouraf.org>