GetArg should explicitly be case insensitive

[denravonska]

It's currently not clear whether arguments are case insensitive or not, see ambiguity when storing and reading the config file. This is possibly an issue when checking if the current private and public keys are valid, see https://github.com/gridcoin/Gridcoin-Research/blob/master/src/rpcblockchain.cpp#L1319.

Improvements:

• See if we can use boost::program_options for writing config values.
• Use case insensitivity in GetArg.
• Try to unit test this.
• Move the many config file and argument handling functions to an args.cpp/h.

Thanks to @Foggyx420 for noticing.

[iFoggz]

has this generally been addresses since the beacon advertising issues are fixed.?

if not we coudl boost:to_lower but some keys like 'PrimaryCPID' and UpdatingLeaderBoard would be affected?