Update the footer links
Support reward_error in client
Change title on Stellar client pages

Normal users don't care that the client is a separate repository from the server, so there's no reason to specify that in the title.
Merge pull request #517 from graysonwright/patch-1

Change title on Stellar client pages
Merge pull request #507 from stellar/reward-error

Support reward_error in client
Switch stg config over to stellar.org
README: Slightly fix contributing instructions
Merge pull request #520 from mc10/patch-1

README: Slightly fix contributing instructions