Copy git lesson files as basis for hg lesson.
Port index and intro pages to hg.
Delete Git staging area image that has no Mercurial counterpart.
Delete image re: Git HEAD~* mapping to rev ids; unneeded for Mercurial.
Port the version control "A Better Kind of Backup" section to Mercurial.
Fix typos re: review by @r-gaia-cs.
README.md: Convert 'boot camp' -> 'workshop'

Following Amy Brown's [1]:

> We borrowed the "bootcamp" terminology from Hacker Within and also
> various fitness training camps, but as we branch out into parts of
> the world with a more violent recent history I'm less comfortable
> with the term.

The consensus on that issue was to change back to our old 'workshop'
terminology.  The swcarpentry/bc repository hasn't made the shift yet,
but there's no reason I can't embrace the future here ;).

[1]: https://github.com/swcarpentry/bc/issues/240
Merge branch 'master' into bc-namespaced

* master:
  README.md: Convert 'boot camp' -> 'workshop'
Merge branch 'bc-namespaced' of git://tremily.us/swc-setup-installation-test into installation-test-bc-namespaced

* 'bc-namespaced' of git://tremily.us/swc-setup-installation-test:
  README.md: Convert 'boot camp' -> 'workshop'

Conflicts:
	setup/README.md

The conflics were due to Ivan's 'boot camp' -> 'bootcamp' changes [1]
which I hadn't pulled into my upstream installation-test branch.  The
end result (using 'workshop' to refer to our sessions) is the same,
but my upstream history just skips the 'bootcamp' phase.

[1]: https://github.com/swcarpentry/bc/pull/174
Initial lesson about python string formatting using the format() method
Removed solutions
Clarified the note about field widths and added an example
Clarified the sentence about the print command output
Fixed typos
Changed line width to 80 characters for the poem formatting and added an explanation
Added machine-readable vs human-readable output, and updated the challenges
02-collab: reorder git and mercurial words
Add materials for python errors lesson
Add "case sensitive" and "traceback" to glossary
Finish lesson with item errors, key points