api: add support for pagination in account, invoice and payment

Signed-off-by: Pierre-Alexandre Meyer <pierre@mouraf.org>
travis: initial import of travis.yml

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

Signed-off-by: Pierre-Alexandre Meyer <pierre@mouraf.org>
payment: add getPaymentMethods APIs

Signed-off-by: Pierre-Alexandre Meyer <pierre@mouraf.org>
pom.xml: upgrade to killbill-oss-parent 0.5.0

Signed-off-by: Pierre-Alexandre Meyer <pierre@mouraf.org>
Merge branch 'initial-version-of-pagination'

Conflicts:
	pom.xml

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