Added MultiBitExchanceExceptionMapper + minor clean-up.
Fixed a bug that was causing incorrect Main-Class to be included in the MANIFEST.MF within web-develop-SNAPSHOT.jar.

Symptom:
[~/project/MultiBitExchange :)   (develop)]  java -jar target/web-develop-SNAPSHOT.jar server mbexchange-demo.yml
Error: Could not find or load main class org.multibit.exchange.infrastructure.adaptor.api.MultiBitExchangeApiWebService
Updated README.md and moved root paths for the test app and api.
Root paths are now:
/app - test application
/api - rest api
/stream - streaming api
Merge pull request #6 from zscott/develop

latest changes