Merge pull request #1 from fsproru/master

Gemify ETL framework
Merge pull request #2 from fsproru/master

Added the Petl namespace and the default rake task
Merge pull request #3 from fsproru/master

Added travis and code climate
Changed namespace Petl::ETL to Petl.
Merge pull request #5 from ZestFinance/feature/fix_petl_namespacing

Changed namespace Petl::ETL to Petl.