Update visualization code to enable parsing and visualization of v2 metrics
These are some cleanups and tweaks I made to the parser and visualization code, most notably to enable parsing of bridgedb-metrics v2. Note that the internal metrics included in version 2 are still not used in any visualization. I've only updated so that the code can still perform the same functions with version 2 metrics by ignoring all internal metrics for now.
In addition, I made a couple of other small cleanup changes:
- I switched the lower and upper bound variables since the recorded values in the metrics data should be the upper bound (since they are the result of rounding up).
- I tweaked the regex used to find non-Tor CC codes to include country codes that include one "z" (eg "az") rather than requiring both letters to be not "z".