Add web UI controls to select 20/50/100/400 previous results

[okurz]

The query parameter 'limit_previous' allows to show more than the default 10
previous results on demand for some time. The current commit adds web UI
selections below the table of the previous build to reload the same page with
higher number of previous results on demand.

Example screenshot:

[coveralls]

Changes Unknown when pulling 81a5023 on okurz:feature/limit_previous_builds_gui into * on os-autoinst:master*.

[coolo]

replace the join('/') with join( ' / ') and it would look better IMO - it's a bit crowded

[okurz]

Well, I knowingly selected this way to write. Let's see if I find some "language related proposals" how it should be done.

EDIT: ok, https://en.wikipedia.org/wiki/Slash_(punctuation)#Spacing confirmed my assumptions: There should only be ' / ' when you want to separate alternatives of multi-word constructs which doesn't apply here. I wanted to write "20/50/100/400" so that people would not confuse it with "Show 20" or "400 previous results" or something like that. Can you accept this?

[coolo]

well, look at our bootstrap table pagination

[okurz]

also I did the "mistake" to record the screenshot at browser zoom of 90%.

Here is the screenshot at 100%:

[coolo]

Just experimenting: https://jsfiddle.net/gp4b0ywy/

[coolo]

Your wikipedia link is pointless btw as it's very uncommon to click on text. While it's pretty common to have spaces around links to make clicking the wanted option more likely

[okurz]

fine, here you go. screenshot in PR description updated

[coveralls]

Coverage remained the same at 68.725% when pulling fbd760e on okurz:feature/limit_previous_builds_gui into c34c90b on os-autoinst:master.