[fix] Added missing text strings

The text strings describing the emacs options in preferences were missing, and are now added.

[Issue: #9]

src/main/resources/l10n/JabRef_en.properties

@@ -673,6 +673,10 @@ Quit\ JabRef=Quit JabRef
 
 Read\ only=Read only
 
+Rebind\ C-a,\ too=Rebind C-a, too
+
+Rebind\ C-f,\ too=Rebind C-f, too
+
 Redo=Redo
 
 Refine\ supergroup\:\ When\ selected,\ view\ entries\ contained\ in\ both\ this\ group\ and\ its\ supergroup=Refine supergroup: When selected, view entries contained in both this group and its supergroup
@@ -903,6 +907,8 @@ Upgrade\ external\ PDF/PS\ links\ to\ use\ the\ '%0'\ field.=Upgrade external PD
 usage=usage
 Use\ autocompletion=Use autocompletion
 
+Use\ Emacs\ key\ bindings= Use Emacs key bindings
+
 Use\ regular\ expression\ search=Use regular expression search
 
 Username=Username