Update `es6-shim` and `sqlite3` dependencies.

Change-Id: I2c3302185f1408a63330333837ebf04f9149a1d0
Correct math handling, adds Standard_deviation testcase

Adds new test for [[en:Standard_deviation]].

I'm not sure if this is the correct solution, but it fixes the crash
and results in math being substituted in to the text output, e.g.:

"""
$$ 2,\ 4,\ 4,\ 4,\ 5,\ 5,\ 7,\ 9. $$

These eight data points have the mean (average) of 5:

$$ \frac{2 + 4 + 4 + 4 + 5 + 5 + 7 + 9}{8} = 5. $$
"""

Change-Id: I83fef6c2d0db9703a3e60acd69d57a547488c56f
Further improve math handling.

Change-Id: Iebe918357851c012225eb80cd39a8d294a76287b
Don't allow version 0.0.24 of the `tmp` package.

Version 0.0.24 of the `tmp` package breaks us, because it changes the
number of arguments to a callback function.  This is because the
`promisify` API in `prfun` is unnecessarily fragile; see
https://github.com/bower/bower/pull/1403#issuecomment-48784169
for some discussion.

Change-Id: I8bc3cd8b63907c68bfd4384d4dc25ad532752d02