Lots of changes

## R/COMPASS.R

- We now default `keep_original_data` to `TRUE`, just so that people
have less to do if they want to run `shinyCOMPASS` on their results.
- We make sure that the `call`’s symbols on the RHS are evaluated,
since they are used for the Shiny app.

## R/shinyCOMPASS.R

- obviate the need for `stimulated` and `unstimulated`, as we can grab
this from the `COMPASS` call.
- meta.vars allows us to choose what metadata variables get into the
data
- obfuscate is used to change PTIDs in case we (or the user) don’t want
those shown externally
- other bug fixes

## Miscellaneous
- Lots of internal changes on the Shiny app (fixed cytokine labels on
line chart, DataTable rendering is a bit better)
- added some more tests for CellCounts