Drop virtualenvwrapper

- Using just virtualenv now if -e flag is used
- Virtualenv will be created in ~/ocw location
Add note about using an alias for ocw activation
Removed the extra second source activate command for conda
Add additional POST INSTALL Message

- Elaborated the POST INSTALL Message when the -e flag is used
- Create a new POST INSTALL Message for those who do not use the -e
option
Merge branch 'CLIMATE-451'

- Resolve PR #57