311 make it easier to set bus speed and so do for bias

[jmmans]

Makes the lpGBT bus speed setting simpler and applies 100 kHz to all the Bias interactions. Probably should change code to restore whatever speed was there before for the non-bias interactions (e.g. ROC)

[tomeichlersmith]

Unfortunately, I am still just seeing a "echo" on the setup at UMN.

 > SET_SIPM 
Which board?  [1] 
Which (zero-indexed) channel? (-1 for all)  [1] 
Which DAC value?  [0] 
 > READ_SIPM 
Which board?  [1] 
Which (zero-indexed) channel? (-1 for all)  [1] 
Channel 1: 0
 > READ_SIPM
Which board?  [1] 
Which (zero-indexed) channel? (-1 for all)  [1] 
Channel 1: 4095