Delete CartoDB::Importer2::Downloader temp files

During the import process, the Downloader class can call
Unp.new.generate_temporary_directory.temporary_directory to create a
temporary directory to store downloaded files. However, this temporary
folder doesn't get deleted after the import process completes, which can
cause the machine running resque tasks to run out of disk space
eventually.

This adds a clean_up method to CartoDB::Importer2::Downloader which is
called after imports complete to remove the temporary folder created by
the downloader.
Be able to dump a user DB through superadmin

Conflicts:
	config/routes.rb
	spec/requests/superadmin/users_spec.rb
Added superadmin specs to Makefile

Conflicts:
	Makefile
Destroy all users after superadmin tests

Conflicts:
	spec/requests/superadmin/users_spec.rb
Added testing attribute
Don't stub user model methods in superadmin tests
Prepares postgres cartodb extension upgrade to version 0.3.4
Merge pull request #660 from CartoDB/CDB-3743

Prepares postgres cartodb extension upgrade to version 0.3.4
Add some relocation fixes
Merge pull request #661 from CartoDB/relocator-fixes

Fix relocation steps
CDB-3761 proper table link qualification
Merge pull request #662 from CartoDB/CDB-3761

CDB-3761
Allow metadata comparer script to be configured with env variables
Merge pull request #663 from CartoDB/compare-metadata-env

Allow metadata comparer check script to be configured with env variables
Documents cartodb postgresql extension upgrade
Stub enable_remote_db_user
sets the right column value
Created cartodb organization factory
Removed debugger
Fixed organization test