Moved contents of util/ to main bin/ directory.

For easier incremental make of command-help docs. There was no
particularly good reason for the separation anyway.
Factored run_get_stdout out of task.py

It will also be used to get cylc version in the repo tree.
Version string for raw source archives.

If in a repository, use git describe; if in a raw source tree use a
VERSION file generated at install time by make.
Update doc/Makefile to prep for raw source archive releases.

1) make generates html or pdf, or both, or neither, according to whether
or not the user has pdflatex and htlatex + convert installed.
2) finally got proper incremental re-make of commands.tex (for when
rebuilding docs in the repository tree).
Replaced "cylc make-release" with simpler admin/make-tarball.

Users will soon download raw source trees from github so we should have
a simple local tarball generator that archives the raw tree just like
github does (no need for a comprehensive test/build-docs/release script
anymore - developers must now run tests and check docs etc. before
merging new features to master).
List contributors in README; include it in User Guide.
made some tabs consistent in doc/Makefile
Correct a newly-modified import statement.
Added build of ext/ordereddict-0.4.5/ to Makefile.
Merge pull request #258 from hjoliver/tidy-for-new-release

Tidy for new release