Upgrade maven license plugin to 2.6, and use the license template instead of custom header, so that this plugin can be executed in submodule directory individually.
Attach license check to validate phase, so that we will not forget to add license header to new file.
Remove copyright headers at the wrong location.
Delete duplicate information from xchange-coinfloor/pom.xml.
Merge pull request #548 from sutra/develop

Upgrade maven license plugin to 2.6 and attach license check to validate phase