Add scale_x_mic to barplot

[natacha-couto]

No description provided.

[jhawkey]

Is this referencing the AMRgen_barplot_mic_gen.R file? If so, scale_x_mic() is currently implemented, line 166. However I think we can add some more options to specify the mic range (maybe based on the max value in the input data?), ie user could specify a minimum value, or a max value, or both, otherwise it's the min-max found in the input