Instal DebugToolbar
Enable DebugToolBar from settings file
Fix typo. Closes #758
Only delete avatar if the user has one
Add documentation
Merge pull request #759 from PyBossa/issue-758-debugtoolbar

Issue 758 debugtoolbar
Merge pull request #762 from PyBossa/issue-fix-uploader-delete

Only delete avatar if the user has one
Merge branch 'master' into issue-658-cache-limits

Conflicts:
	pybossa/core.py
	pybossa/default_settings.py
	pybossa/extensions.py