Changed EULA to Yes/No to Agree/Disagree

EULA

@@ -3,5 +3,3 @@ This is a PREVIEW RELEASE of a client application for the Let's Encrypt certific
 Until publicly-trusted certificates can be issued by Let's Encrypt, this software CANNOT OBTAIN A PUBLICLY-TRUSTED CERTIFICATE FOR YOUR WEB SERVER.  You should only use this program if you are a developer interested in experimenting with the ACME protocol or in helping to improve this software.  If you want to configure your web site with HTTPS in the meantime, please obtain a certificate from a different authority.
 
 For updates on the status of Let's Encrypt, please visit the Let's Encrypt home page at https://www.lets-encrypt.org/.
-
-Do you accept?

letsencrypt/client/client.py

@@ -60,7 +60,7 @@ class Client(object):
         # Display preview warning
         if not eula:
             with open('EULA') as f:
-                if not display.generic_yesno(f.read()):
+                if not display.generic_yesno(f.read(), "Agree", "Disagree"):
                     sys.exit(0)
 
         # Display screen to select domains to validate

letsencrypt/client/display.py

@@ -98,7 +98,7 @@ class NcursesDisplay(Display):
         return self.d.inputbox(message)
 
     def generic_yesno(self, message, yes = "Yes", no = "No"):
-        a = self.d.yesno(message, HEIGHT, WIDTH)
+        a = self.d.yesno(message, HEIGHT, WIDTH, yes_label = yes, no_label = no)
 
         return a == self.d.DIALOG_OK