Fix grammar in registration prompt

[sooskriszta]

http://buddypress.org/support/topic/how-can-i-change-the-text-to-make-it-literate/#post-172507

On the registration page:

“Registering for this site is easy, just fill in the fields below and we’ll get a new account set up for you in no time.”

It’s called a comma splice: The use of a comma where a period or a semicolon should go.

Fix: Change comma to semicolon.

[boonebgorges]

In 7408:

Remove comma splice from registration template.

Fixes #5195

Props sooskriszta