Ring in MDV files used in examples

[zssherman]

Notice that a a few of the mdv example plots have a high DBZ ring at the furthest gates that create a high DBZ circle. Might need to determine if this is the files or the code itself.

[mgrover1]

I took a closer look at some of this behavior - it looks like this could be more a data file issue... here is a plot of single ray

Notice how the last few gates have very high values, but taking taking a closer look at the data values, they are not set to a single high value (ex. 60 dBZ), but rather, a variety of higher values...

[mgrover1]

Discussion continued in #1331