Edited installation materials to match package

setup.py and PyPI expect you to pip install easy-thumbnails. The docs proper have this correct as well, but the readme is incorrect.
Merge pull request #171 from adamfast/master

Update README with current installation information
Fix error with widget and uploaded images.
Small fix
Merge pull request #178 from camilonova/patch-3

Minor documentation fix
Add test for widget and uploaded images.
Merge pull request #167 from selwin/master

Pass in file name to Thumbnailer when saving field with "resize_source" (issue #137)
Fixed deprecation warning

`django.utils.hashcompat` is deprecated as of Django 1.5. Use `hashlib` instead.
Merge pull request #187 from gjb83/master

Fixed deprecation warning
Merge pull request #174 from zlorf/master

Fix error with the widget choking on uploaded images

Thanks Jacek Tomaszewski!
Consistent <img> html format in readme

Also fix a half finished sentence.
Added section on Asynchronous Pregeneration
Merge pull request #190 from gjb83/master

Added doc section on Asynchronous Pregeneration

Thanks gjb83!
Added Django 1.5 compatibility - mode on file-like object is not set in django anymore
Small style change
Fix a failing test
Release a 1.5 compatible version
`hashcompat` is deprecated as of Django 1.5

django.utils.hashcompat is deprecated as of Django 1.5. Use hashlib instead.
Merge pull request #198 from jaap3/hashcompat

`hashcompat` is deprecated as of Django 1.5
Possible solution for issue #175