cmd/hiveview: multiple UI improvements

[skylenet]

Some new features:

General:

• Allow passing --limit to the hiveview --listings command. So that we can decide how many we want to index. Still kept 200 as default.
• Added client versions to the hiveview --listings output, so that we can show them on the index page.

Index:

• Summary on top, that has a box for each simulator/client pair that was run. Sortable by name,coverage or time.
• Clicking on the box brings the user to the table view, where all the past executed tests can be seen (filtered by sim/client pairs)
• Added a diff column, that shows a counter of + or - passed
  tests, compared to the previous test run (from the same simulator + client pairs)
• Generally adding a bit more colors and smaller design adjustments
• Show the specific client version in the table
• Added some keyboard shortcuts

Suite page:

• Allow rendering html within the test description. Used a lot by the ethereum/eest simulators, where they show how to reproduce a specific test.
• Show total passed/failed tests stats on the top right and add colors to it (green -> passed, red -> failed)

Viewer:

• Add log syntax highlighting using prism

[marioevz]

Looks absolutely amazing, thanks for this!

cc @fjl on final check for this since he is the owner of all of these files :)