Add Sphinx documentation directory

Generated with 'sphinx-quickstart' tool.
Add API reference documentation

The files were generated using 'sphinx-autodoc'.
Add installation instructions
Add basic usage documentation
Add preliminary development documentation
Add LaTeX preamble to increase TOC depth
Add command man page generation
Merge branch 'new-tools' into documentation
Update docs to reflect flat commands structure
Move API Reference into an organised file
Add basic documentation for budget commands
Merge branch 'new-tools' into documentation
Make budget a single module

After it was moved from a package to a module.
Pick up docstrings by fixing sys.path

Per the documentation above it, we know that the module in question
is in the root of the repo, not in the docs folder.

Change-Id: I5b435770794663a0541246d32aa3952fd47c1f28
Add docs on how to configure the tools
Add docs on making inventory queries
Add more docstrings to inventory tools
Add a load of one-liner docstrings

Should mean that every function is at least documented.
Merge branch 'new-tools' into documentation
Move oldinv function into inventory

Also take the opportinuty to improve the API and write some docs.