config: fix talking clock regexes (need ^ and $ so they don't match only 917x)

conf/dialplan/default/01_Talking_Clock.xml

 <include>
   <extension name="Talking Clock Time" ><!--e.g. 10:56pm-->
-    <condition field="destination_number" expression="9170">
+    <condition field="destination_number" expression="^9170$">
       <action application="say" data="en CURRENT_TIME pronounced
 				      ${strepoch()}"/>
       <action application="hangup"/>
@@ -8,7 +8,7 @@
   </extension>
   
   <extension name="Talking Clock Date" ><!--e.g. March 8, 2011-->
-    <condition field="destination_number" expression="9171">
+    <condition field="destination_number" expression="^9171$">
       <action application="say" data="en CURRENT_DATE pronounced
 				      ${strepoch()}"/>
       <action application="hangup"/>
@@ -17,7 +17,7 @@
   
   <extension name="Talking Clock Date and Time" ><!--e.g. March 8, 2011
 						     10:56pm-->
-    <condition field="destination_number" expression="9172">
+    <condition field="destination_number" expression="^9172$">
       <action application="say" data="en CURRENT_DATE_TIME pronounced
 				      ${strepoch()}"/>
       <action application="hangup"/>