Fix typo in README
Fix travis build (ignore lines > 80 chars)
added a object implementation of screenshot, with some kind of caching through a manager
pep8
add SCREAMSHOT_AS_INSTANCE setting to set WebPageScreenshot class abstract or not (default: abstract)
cleanup
move SCREAMSHOT_AS_INSTANCE to app_settings in __init__.py
Merge branch 'master' of github.com:lucmilland/django-screamshot

Conflicts:
	screamshot/admin.py
	screamshot/models.py
typo + pep8
import datetime in place of django.utils.timezone for django versions < 1.4
added django-timedeltafield dependancy to .travis.yml
Merge branch 'master' into devel
add django-timedeltafield dependency in setup.py and drop travis support for django 1.3 and 1.4