Support strings as attribute names

When generating the `_fast_attributes` method, attribute names that
could not be represented as symbols (at least without escaping) would
throw parsing errors.
If output is as expected, is this assert important?
Use method instead of asssociation_ids if method exists. Fixes #267
Fix serialization_scope to check for private/protected methods

The semantics of respond_to? on Ruby 2.0 have changed to return false for protected methods, which is usually the case for helpers like current_user.
Merge pull request #276 from darthdeus/patch-1

Fix serialization_scope to check for private/protected methods
Let's not let edge rails break travis.

We want to run tests against edge rails, but we don't want their build to break ours. So it
goes in allow_failures.
Merge pull request #268 from vanstee/escape-attribute-names

Support "unsymbolizable" strings as attribute names
Merge pull request #273 from seanabrahams/embed-ids-not-using-local-method

Fixes #267
Update CHANGELOG.md

Make it more consistent.
I've added some PR titles to 0.7, I'm not sure it's 100% comprehensive like this :(
The version numbers must match rubygems versions, I fixed it here.
Thanks
Merge pull request #277 from gravis/patch-1

Update CHANGELOG.md
Switch back to the old hash syntax

Just fixed up a couple of hash literals in the tests so that the build
passes for 1.8.7
Merge pull request #278 from vanstee/use-old-hash-syntax

Fix the build in 1.8.7