Add test for monetary value formatting

Tests for issue #3126.
This problem pops up after upgrading json-spirit.
Merge pull request #3133 from laanwj/2013_10_format_monetary_test

Add test for monetary value formatting
Add test for monetary value parsing

Just-in-case sanity test for JSON spirit and AmountFromValue.
Also update rpc_format_monetary_values test to use ValueFromAmount,
so that ValueFromAmount is also tested.
Merge pull request #3134 from laanwj/2013_10_format_monetary_test

Add test for monetary value parsing