API documentation uploaded

Carlos is continuing work, with some help from the community, on the ZODB book.  Currently you can see daily updates at http://zodb.readthedocs.org.  The new API section, http://zodb.readthedocs.org/en/latest/api.html lists the entire zodb/transactions API on one page -- thanks Dag Odenhall. Now if we could get richer descriptions on the method's.  We are looking for volunteers.  Some suggested topics:

• Conflict resolution
• BTree usage
• ZEO aka "Client Storage"
• Demostorage usage and real world examples
• PickleCache

All work is on github, https://github.com/cguardia/ZODB-Documentation