Working n orders depth exchange rate
working depth based on amount, depth 0 for last offer midpoint
some syntax changes
ability to specify depth for each pair added
removed depth = 0 when no depth specified
removed logging
Merge pull request #5 from vahaknp/develop

Add 'live' option to exchange rate
fix bug with issuer capitalization
Merge pull request #6 from ripple/develop

exchange rate via rippled and issuer cap fix