RJSONIO fix.

Following suggestion at
http://stackoverflow.com/questions/17181212/r-package-with-dependency-on-shiny-gives-rjsonio-warning
moving from Depends to Imports
and removing library calls in server.R.
For more on Depends versus Imports, see

http://stackoverflow.com/questions/8637993/better-explanation-of-when-to-use-imports-depends
http://stackoverflow.com/questions/9893791/imports-and-depends
Getting rid of the rm() call at the top of server.R
Added stringsAsFactors=FALSE
to data.frame calls.
Sheesh. Bitten by the factor zombie again.
Lots of improvements in the writing and details.
Allow running the shiny interface on the locally edited file without reconstructing the package.
Use arg local=TRUE
Testing out ideas about variables, parameters, generating outputs ("provisions") etc.
Ok, we have a mechanism for evaluation.
This line:
  evaluateOutput(clearanceRate, list(B=0))
works fine.
I don't know how it finds rnorm,
but I'm glad it does!
The main problem was that using a variable name "sd"
captured the sd function instead of the value.
Changed to sdev, now it works.
This shows that you don't have to add in baseenv
(but I thought you did...)
Bumped version and date.
This shows that,
if necessary, we can parse the body of the generator function for output variables.
(But it may not be necessary.)
Learning more, making progress,
but not quite there.
Simplified, better documentation, for evaluateOutput().
This seems a little more reliable way of getting the inputs into the function.

Somehow we managed to add B to package:base!!
And can't get it out!!
From earlier, when we had a line
  list2env(params, baseenv())
Defined extractRequirements and extractProvisions.

Beginning work on toxDoseThreshold.