Rename get_graph() -> execution_graph

Instead of having a generic get_graph()
it is nicer to have this function be named
closer to what it returns (the graph of tasks
to be executed) as well as make it a property
since it is more of a property of the engine.

Change-Id: I4bb458b1069d7e6877f1cc51d42bfc0d8c751951
Add a persistence util logbook formatting function

It is quite useful to be able to dump what is in a
logbook in a human readable format so this adds a
helper utility function to do just this.

Change-Id: I84d8a9caf531de018fb361211624fc5b8c030260
Save with the same connection

Instead of 2 different connections, one
for saving the flow detail and then one
for saving the task detail just use one
connection for both.

Change-Id: I68315a6c201325bb154f5ab5fc69a3824055c912
Add more comments to flow/task

Increase the number of comments which
will help users of these 2 modules better
understand there desired usage.

Change-Id: Ief248770de3bedd7fc87bfcfbce4da77c011de7f
Pattern comment additions/adjustments

Change-Id: I3154d1c228474d8699f3ae4d0be2fb46406a2f41
Beef up the action engine comments

Also make a few minor tweaks to the
underlying functions and relax the
networkx requirement slightly.

Change-Id: Ibbfa7f786d3c33956f7ca39b7ea9423696859e45
Comment additions for exponential backoff

Change-Id: If43d6e5ceedc17b1763ecd8a244f959150b802e1
Create logbook if not provided for create_flow_details

This simplifies code and gives flow details correct name even
if log book was not provided.

Change-Id: Icef03ff843002f15c3ed90fd8c44d69c0bd4d9f0
Storage: add flow name and uuid properties

This commit adds flow_name and flow_uuid properties to storage.
We also add couple of unit tests for storage while we are at it.

Change-Id: I58e6fcf7e799d7a69d75eab4fdc40400c1dc488d
Helpers to save flow factory in metadata

This change adds new helpers that, taken together, allow to resume
the flows having nothing but flow detail at hands. First one,
load_from_factory, gets flow factory function as a parameter and
saves its fully qualified name and arguments to flow metadata. Others
can be used to re-create the flow using that metadata, and load
it into engine.

Change-Id: Ia3cd989b3b0388ec0a9f09fe527f768eec5cc904
Removed unused utilities

Change-Id: Ifa3e7b820d594303c6c02eae12f55bce2bd1dacc
Merge "Rename get_graph() -> execution_graph"
Merge "Save with the same connection"
Merge "Add a persistence util logbook formatting function"
Merge "Beef up the action engine comments"
Merge "Comment additions for exponential backoff"
Merge "Pattern comment additions/adjustments"
Merge "Add more comments to flow/task"
Beef up storage comments

Add a few comment adjustments and changes to
the storage layer code comments.

Change-Id: I6e8ca80473d4db7588aeacb06d00e5d6774e4f7e
Merge "Create logbook if not provided for create_flow_details"