Make implicit knowledge more explicit in getting_started doc

Add more clear instructions on how to acquire the oh-mainline source
code.

Closes ticket https://openhatch.org/bugs/issue101
Merge pull request #300 from onceuponatimeforever/install_docs

Make implicit knowledge more explicit in getting_started doc
Fixed #990 Deleted references to geolocation, maps, guessing location

Deleted code in the settings page that has any mention of geolocation and maps,
including geo-location-related html, views, and tests.

Changed default url link "settings" on header from
/settings/location/ to /settings/invite_someone.

Made design decision to re-structure left-hand navigation bar on
settings page in order to improve UI:
    "Tell friend about OpenHatch" tab appears first on top left,
    followed by the "Widgetize yourself" tab, and finally,
    the "Email", "Name", and "Password" navigation tabs.

Made design decision to have the message "If you want us to forget your
location, empty out the text field and hit save" appear as the default
location message in settings page.
Merge pull request #273 from onceuponatimeforever/990-new

Fixed #990 Deleted references to geolocation, maps, guessing location