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
Init. commit of (medical) image processing ipynb.
Add height to Eventbrite iframe

and values for when using two rooms.

**The height provided isn't suitable for small screens.**

Close #493.
Made changes suggested by Will Trimble - change Lena for Sally Ride.
Downsampled image to sensible size and removed references to SciPy Lena.
Simplified introduction by removing complicated colourbar placement stages.
Finished cleaning up IPYNB to show Gaussian fit to background.
Small edits to novice R lesson on functions.
Updated section on defining an R function.
Indent with 2 spaces instead of 4. This is in agreement with Hadley and Google style guides.
Updated Composing Functions.
Added first call stack image.
Added stack frame images and explanations.
Replaced section on scoping and environments with short Tip that points to outside references.
Updated section on encapsulation.
Replaced exercises using paste and strsplit with easier exercises that simply slice vectors.
Updated challenge on drawing stack diagram with nested function calls.
Updated section on testing and documenting functions.