Merge pull request #461 from PyBossa/generalise-importers2

Generalise importers2 - abstract beyond HTTP lookups of files
move importers to own file
remove extraneous dummy var in destructure
Merge pull request #462 from PyBossa/generalise-importers2

Generalise importers2 - prepare to move importers to own file
Merge branch 'master' into culttag-redux
manual merge