Added a getFriendlyString method

Added the ability to get a friendly string representation of a numeric,
which will respect the sign if specified.

ie:
1000 -> 1.0K
100,000 -> 100.0K
1,000,000 -> $1.0 million
1,000,000,000 -> $1.0 billion
1,000,000,000,000 -> $1.0 trillion