Allow disabling periodic committing when inserting rows with DbApiHook

[underyx]

>>> i = 1
>>> commit_every = 0
>>> bool(i % commit_every == 0)  # previously
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ZeroDivisionError: integer division or modulo by zero
>>> bool(commit_every and i % commit_every == 0)  # with this change
False

[landscape-bot]

Code quality remained the same when pulling 7a31361 on underyx:patch-1 into 58df89f on airbnb:master.

[coveralls]

Coverage remained the same at 66.377% when pulling 7a31361 on underyx:patch-1 into 58df89f on airbnb:master.

[mistercrunch]

It would be nice if you added a definition of the parameters in the docstring, their expected types and special cases (like handling of 0) you just added. There are examples in the codebase as to what the param should be for the auto-docs to format it nicely. Are you up for it?

[underyx]

Yeah, why not, @mistercrunch. I'll do it later today, hopefully.

[underyx]

@mistercrunch well I guess I didn't do it 'later that day' in the end. PR might be ready to merge now, though!

[landscape-bot]

Code quality remained the same when pulling b940706 on underyx:patch-1 into 58df89f on airbnb:master.

[coveralls]

Coverage increased (+1.6%) to 67.998% when pulling b940706 on underyx:patch-1 into 58df89f on airbnb:master.

[r39132]

@underyx Please squash commits and ping me on gitter when ready to merge again