look for pre/post-processors using _SINGLE and _MANY suffixes

This code previously was looking for pre/post-processors on `PUT`, and
applying them to `PATCH`, but the correct keys are `PUT_MANY`, `PUT_SINGLE`,
`PATCH_MANY` and `PATCH_SINGLE`.
Update docs/basicusage.rst
AssociationProxy fields don't have a property value

Instead, pass through to the real field on the remote table, so it can be checked for whether or not this is a date value.
Merge pull request #142 from glyphobet/put-processors-apply-to-patch

look for pre/post-processors using _SINGLE and _MANY suffixes
Merge pull request #143 from schlamar/patch-1

Update docs/basicusage.rst
Merge pull request #147 from glyphobet/date-field-association-proxy

AssociationProxy fields don't have a property value
Fixes #146.
Fixes #141.
Really fixes #141, with Python 2.5 compatibility.
Fix typo in comments.
Adds an example for using the requests library as a client.
Organizes examples into subdirectories: one for client examples and one for server examples.