Fix app initialization with resource level versioning

When using resource level versioning, the initial iteration to register
each resource would raise a RuntimeError because of versioned resources
being inserted into DOMAIN at the same time it's being iterated. A
snapshot of DOMAIN is used for iteration to fix this.

Also, new versioned resources are passed through _add_resource_url_rules
to fix some tests needing them to be in config['URLS'].

This doesn't add tests for this specific case but adds a new
`versioned_invoices` resource to eve.tests.test_settings with
versioning enabled in the resource level.
Merge branch 'fix/init-runtimeerror-with-resource-versioning' of github.com:sebasmagri/eve into sebasmagri-fix/init-runtimeerror-with-resource-versioning
Do not follow DATE_FORMAT for HTTP headers (fix #429)
Test that post_internal() is properly functioning.

Integrates #416 tests and also update the relevant docstrings.
proper favicon path
Alabaster sphinx theme
fix embedding of subdocument into missing field
Hidden TOC; use sidebar instead.
Merge branch 'develop' of github.com:aikoven/eve into aikoven-develop
Revert "Hidden TOC; use sidebar instead."

This reverts commit e972c530e4110c9c4b6d99bdaf2f3dae7432379a.
Use custom 'Fork me on Github' banner with Alabaster theme
add test for embedding into a missing field
Merge branch 'develop' of github.com:aikoven/eve into aikoven-develop
Daniel Lytkin
Fix KeyError when embedding on a missing field.

Addresses #319 and #433.
Merge branch 'aikoven-develop' into develop
Docstring fix. Closes #432.
REST API for Humans
typos, and rephrasing
Sebastián Magrí