Add state to dot->svg tool

Add a helper tool that can convert the
allowed state transitions into a dot graph
which itself then converts it into a browser
compatible svg file, which can then be looked
at to have a pretty state diagram.

Change-Id: I3cbbc75bd58182700ddc07f00395da5d1093a26c
Create a green executor & green future

In order to use the multi-threaded engine
which takes an executor as input for projects
which have *not* eventlet monkey patched the
threading module we provide a eventlet
compatible executor and future objects which
can work with the same multi-threaded engine.

This executor also works in natively threaded
applications by correctly altering the future
condition attribute to use a greened condition,
which is required to make sure that greenthreads
run when the condition is waited on.

blueprint eventlet-engine

Change-Id: Ida9ce6183471ad6b323a3c9ca863561699e32ddc
Resumption from backend for action engine

Simple refactoring and minor code adjustments to make resumption
from backend actually work:
- call engine.compile and check for missing dependencies
  on every run;
- misc.Failure equality semantics adjusted;
- load failures from backend on every run.

Change-Id: I8a0462f2dec0ec66a19ee6a5ef10e4be48110e19
Merge "Add state to dot->svg tool"
Merge "Create a green executor & green future"