Navigation and gdp

[smitjuli]

This pull request makes the following changes:

• imported bootstrap css files to project
• adds navigation bar with buttons and spacing
• removed "about us" link at the bottom of pages
• changed text headers on home page to tell better "narrative"
• updated gdp page text
• fixed miscenllaneous spacing and spelling errors

[smitjuli]

closes #64 closes #51

[smitjuli]

resovlve merge conflicts between navigation-and-gdp and master branches