fix ** conflict with *, triggered while typing **<tab> snippet will

expand into `* *{e}*`. I change into `*&` user still don't have to
release their Shift key

snippets/rst.snippets

@@ -4,7 +4,7 @@ snippet :
 	:${1:field name}: ${2:field body}
 snippet *
 	*${1:Emphasis}* ${2}
-snippet **
+snippet *&
 	**${1:Strong emphasis}** ${2}
 snippet _
 	\`${1:hyperlink-name}\`_
@@ -62,8 +62,8 @@ snippet sid
 		
 		${2}	
 # CJK optimize, CJK has no space between charaters
-snippet *c
+snippet *!
 	\ *${1:Emphasis}*\ ${2} 
-snippet **c
+snippet *&!
 	\ **${1:Strong emphasis}**\ ${2}