Cleanup hostname status images both for workers and devices.

Slight performance improvements observed with page load.

See:
  - http://goo.gl/XAzAbL
  - http://goo.gl/sOSf2s

Change-Id: Ia64d92cf22a74e53e1533488a59a1e0893e51489
Sum up the test results when there are parametrized tests in bundle.

Fixes bug 587 (https://bugs.linaro.org/show_bug.cgi?id=587).
Also includes small fix for 'toggle legend' positioning.

Change-Id: I8081a6787b7029f35ff3feedb5f61df2f0444c22
Add skipped and unknown test count to totals in image reports.

Also adds skiped count to tooltip.

Change-Id: I7cb448b79976da097f3c911607505ffd5361d985
Add information about lava-network cache file.

Change-Id: I01fcafaf238f472bc9ce892eeb894335c66989ba