Fix ABR controller if min allowed bitrate is set

[bbert]

Before the fix:

• set min allowed bitrate on player, for example 500kb/s
• start a new stream
• ABR controller selects highest quality as initial bitrate, for example 2Mb/s, since previous bitrate stored in local storage is high

=> then at first pass in ABR controller before downloading 1st video segment:

• no rule is applied
• a switch request with NO_CHANGE quality (=-1) is applied
• this quality (-1) is compared to min allowed quality
• since -1 < min allowed quality, min allowed quality is selected instead of highest quality

This PR fixes this issue.

Additionnaly, this PR adds the possibility to set min and max video bitrate in the options of the dash-if-reference-player sample webapp.
And it fixes also the assignement of ABR settings in the webapp.