fixed python 3 issue with str having __iter__ attribute

ParseResource's need to know they've been loaded

In __getattr__ we check to see if the object has been lazy loaded or not
before we try to do attribute lookups. However, once the attributes have
been loaded, we never record that.

So this changes _init_attrs, which actually does the loading, to record
that it's done so.

This change took a loop I had that was taking 8-10s to finish down to
.5-1s.

Fix the relatedTo Query operator

Basically, if we're asked to convert_to_parse a list, do it for
everything in the list and return the list.

All of the tests pass now, so I don't believe anything has been harmed
in this change.

It currently fails because:
  TypeError: <Game:XKz5Hfyxqw> is not JSON serializable

Before this we were never passing in all of the data required for the
relation lookup to work.

Figured this out after looking at the 4th code example at
https://parse.com/docs/rest#queries-relational and comparing to the
request that was actually being sent.

All the tests pass now.

Making an Object, and then marking that it's got Relation's doesn't
work. These tests demonstrate that. Next commit will fix whatever's
needed so that these tests pass.

great, thanks

Add timeout to urlopen

- Connection can sometimes hang forever on SSL handshake

eg Subscription.Query.get(user=User(objectId='foo'))

Python3, tests for new features, small fix for __len__ and query copying

Object.factory returns user defined types if exists. Also returns same type for two calls with same arguments.

independent derived queries - filter, limit, skip, select_related methods returns queryset copy instead of self

This is proper implementation of idea suggested by orignal limit and skip methods based on metaclass (but not working at all)
It works same as Django queries - original unfiltered query can be still executed or used to create
different filter.

made skip and limit consistent with other query methods

select_related feature, result cache +  few updates to have more Pythonic code

selected_related - Django like method to declare related objects fetched with based query (using 'include' parameter from Parse API)

https://www.parse.com/docs/rest#queries-relational

it supports setup.py develop

Added README and unit tests on Push functionality. Changed functionality slightly to allow channels= to be specified alongside a where= argument.

convert Date to iso8601 with 3 digits microseconds

Fixing buggy interaction with Cloud Code

Set up cloudcode directory as package_data so it would be included in tests not run in the downloaded directory. Also set up a tests.run_tests() function so that one wouldn't have to download setup.py to run tests, and modified README. Fixes #37