writting CubeJoin class
used to process merge cube
if process cube join call class CubeJoin
central merge cube
Fix pep8 on utils pandas
E302 expected 2 blank line
remove field _id on cube load
fix firefox crash and changes Data lists
Merge branch 'master' into layout

Conflicts:
	mining/assets/app/views/cube.html
	mining/assets/app/views/dashboard_detail.html
new alias and show fields flow