Adds additional instructions

- Adds link to wiki, where instructions for difference system
configurations can be built out.
- Adds additional info about where cloning the repo will place download
it to.
Adds instructions on where to go to test the running instance

Readme instructed reader to run the app but didn't direct them where to
go to see the app running. This commit adds a message informing the
user where to go.
Updates readme

Port number shown was incorrect
Updates readme

- Removes link to main wiki.
- Adds link to installation instructions page.
Merge pull request #39 from codeforamerica/readme-updates

Readme updates