More PHP 5.4 backwards compatability. SplObjectStorage internally checks if object exists on attach and detach so preserve this behavior on our fallback approach. Includes create_vertex function that lets you control how get_vertex will behave and can act as a factory for your vertices.
Add some helper functions that may add increased flexibility for naming vertices in your graph if you have parent classes.
Merge branch 'master' into feature/v0.9

Conflicts:
	src/CentralDesktop/Graph/Graph.php
	src/CentralDesktop/Graph/VertexSet.php
Revert "Revert "Utilize __toString since that's kind of why that was implemented in the first place.""

This reverts commit 33cdcd63a7e7c1ab9780f12df2fdf4e9377b8969.

Conflicts:
	src/CentralDesktop/Graph/VertexSet.php
Revert "Revert "SplObjectStorage implemented getHash in PHP >= 5.4.0. Implement temporary backwards compatability to support control of object hashes so we can easily fetch vertices by data.""

This reverts commit 61248945594219da36747b8648fc99f65f0889c2.

Conflicts:
	src/CentralDesktop/Graph/Graph.php
	src/CentralDesktop/Graph/VertexSet.php
Fix bad revert
Remove check on has vertex. Grabbing the outgoing edges and comparing our source and target will accomplish the same thing.
Merge branch 'feature/v0.9' of github.com:centraldesktop/graph into feature/v0.9
Merge branch 'master' into feature/v0.9
Merge branch 'feature/v0.9' into feature/v0.9.1
feature() Remove PHP 5<5.4.0 compatability.
Merge branch 'feature/v1.0'
chore() changelog 1.0.0