Add an error handler to simple_recipe

When the NothingToDoException is raised from simple_recipe(),
it is assumed to be an error, which needs to be handled.
If it is not handled, it results in "Unhandled error in
Deferred" messages being spewed after the recipe is completed.

This patch adds an error handler for NothingToDoException
and the base Exception class. The latter is added to handle any other
exception that may be raised from run_task(). The idea is to add an
explicit error handler and take appropriate action depending on the
Exception thrown.

Bug: 1004381
Change-Id: I3b89a1dca309b5eb9f2fc0cdc028792eb28ba940
Documentation reorganization

The documentation now lives in documentation/ as a Sphinx
project. Older standalone documents which did not fit in entirely
or partially are kept in their original form in legacy/.

Change-Id: I978dcd6803730fccc27338f26e7a03cbc03d82c0
Add a new README and remove build.sh
Merge "Documentation reorganization" into develop
Merge "Add a new README and remove build.sh" into develop
Add a version string.

Change-Id: I16b0d3a936d14025c07b91f2f905aa7dc35ba2e8
Changes to Documentation

- No custom style (Use default Sphinx theme/templates)
- Removed documentation on environment variables and continue
  maintaining it as part of the Beaker docs tree
- Cleaner conf.py

Change-Id: I3f6ac0414ac29cb0fac3b460e564cbea761f9e0b
Automatic commit of package [beah] release [0.6.47-1].