Fix SharedDataMiddleware.generate_etag

Previously this failed on non-ascii paths
Properly retrieve PATH_INFO in SharedDataMiddleware
Added changelog entry for shared data middleware fixes
Merge branch '0.9-maintenance'
Automatically handle Expect: 100-continue in the development server.
Fixed exhausting not working in all cases in the multipart parser.

Raised buffer sizes.
Release date for 0.9.1
Bump version number to 0.9.1
In case we need a 0.9.2
Merge branch '0.9-maintenance'
Made tiny changes to the security module's docstrings to improve readability.
Improved error message to tell not only what is wrong, but also _why_ it is. Kinda.
Merge pull request #390 from homeworkprod/doc-fixes

Made tiny changes to the security module's docstrings to improve readability.
Merge pull request #391 from homeworkprod/better-error-message

Improved error message to tell not only what is wrong, but also _why_ it is. Kinda.