Various improvements

• Use log4j2 in test-project
• Support injecting header values via method arguments
• Improve error handling for service injection
• Allow controllers to return ApiGatewayResponse objects directly

Allow specifying header for binary repsonse

v0.3.1

Increment version

Support binary response data

v0.3.0

Increment version

Initial public release

v0.2.0

Upgrade bintray plugin