stbt.Display.__init__: (save-video) Remove unnecessary argv[0] check

The only callers of `stbt.Display.__init__` are:

    stbt.Display.__init__
    ↳ stbt.init_run
      ↳ stbt-run: stbt.init_run(..., args.save_video)
      ↳ stbt-record: stbt.init_run(..., False)

`stbt-record` calls `init_run` with `save_video=False`, so it is
redundant to check that `argv[0] == "stbt-run"`.

Thanks to Bryce Gibson for pointing this out:
https://groups.google.com/d/msg/stb-tester/jEBSeS9-l2c/LXX7J2DAcpgJ
test_runner_sigint_*: Increase timeout for runner to start

On a heavily loaded system this timeout wasn't enough. Only seen on
the travis-ci service that runs our self-tests in the cloud.
runner: add tablequeryjs to reports to allow textual filtering

This commit adds tablequeryjs [1] to stb-tester runner reports. This is
useful because it allows Wireshark-like text-based filtering of the HTML
table, executing queries such as:

- `tag ILIKE slave-1 or tag ILIKE slave-2`
- `"exit status" ILIKE "^(1|2)$"`

Currently tablequeryjs depends on both jQuery and jQuery UI. Removing
the latter as a dependency is tracked in [2] and I hope to get around to
this soon. There are also numerous usability improvements, all tracked
in issues, that I'm hoping to implement soon as well.

[1] https://github.com/asimihsan/tablequeryjs

[2] https://github.com/asimihsan/tablequeryjs/issues/4
extra/runner summary report: Keyboard navigation skips hidden rows

The filter functionality added in 175a9f55 can hide table rows; pressing
the "up" and "down" arrow keys now skips hidden rows.
extra/runner summary report: Filter's placeholder text gives example

To give users an example of the syntax accepted by this filter, and so
that they know there is an "ilike" operator.
Merge branch 'runner-tablequeryjs'

* runner-tablequeryjs:
  extra/runner summary report: Filter's placeholder text gives example
  extra/runner summary report: Keyboard navigation skips hidden rows
  runner: add tablequeryjs to reports to allow textual filtering