Incorporate README feedback

README feedback from Rob Williams (AAR):

```
- Directory references in the config files shouldn’t end with “/”
 
- The nginx.conf configuration instructions say the following:
Replace <%= nginxConf.LOCAL_FILE_STORAGE_DIRECTORY %> with the full absolute path that you configured for file storage in the Hilary config.js step
…however, the configuration of this parameter is never described in the config.js section.  I had assumed that it was referring to the config.files.uploadDir in that section.  It would clear things up if  config.files.localStorageDirectory was mentioned in the config.js section, and referred to by name in the nginx.conf instructions to clarify.
 
- Under ‘Starting the Server’ it could use instructions on how to run the node command as a background process (similar to the instructions for the other apps).
 
- In the ‘Apache Cassandra’ section, when setting permissions for ‘whoami’, it would help to specifically state that ‘whoami’ should be the user who will be starting Cassandra.  It’s easy to come to that conclusion if you know chmod, but I’ve been tripped up in other docs before because their ‘fake user’ looked an awful lot like a command parameter J
```