Ebaysdk

- merge in pull request to fix unicode issues
- remove PyYAML dependency
- add poller package for pulling orders

- modify install instructions
- remove grequests install dep from setup.py

- WARNING!! This release breaks some backward compatibility
Read https://github.com/timotheus/ebaysdk-python/wiki/Migrating-from-v1-to-v2
- imports: Modified package structure
- execute(): Modified return value
- Switched to lxml.etree
- Added a new response class
response.reply, response.dom(), response.dict(), response.json()
- Added ebaysdk exception classes
- Modified utils.py (dict2xml, xml2dict)

- rework unicode fix
- fix logging handler

- fix unicode issue is dict to xml routine
- add a unicode test
- fix http back-end

- Major refactor
+ changes are backward compatible unless your subclassing any of the
SDK classes
+ moved from PyCurl to Python Requests
+ code organization
+ standard python logging
+ add exceptions