Clean up file names

CDMG/cdmg.css

@@ -133,7 +133,7 @@ button[type=roll].sheet-stat-roll::before {
     cursor: pointer;
 }
 .sheet-collateral-damage label input[type=checkbox]:checked + span:before {
-    content: url("https://raw.githubusercontent.com/patschroed/roll20-character-sheets/master/CDMG/heart_slash.png");
+    content: url("https://raw.githubusercontent.com/patschroed/roll20-character-sheets/master/CDMG/heart-slash.png");
     cursor: pointer;
 }
 .sheet-collateral-damage ul {

CDMG/cdmg.html

@@ -2,7 +2,7 @@
     <!--Logo / Player Name / Movie Title -->
     <div class="2colrow">
         <div class="col">
-            <img src="https://github.com/patschroed/roll20-character-sheets/blob/master/CDMG/CDLogo_.png?raw=true" />
+            <img src="https://github.com/patschroed/roll20-character-sheets/blob/master/CDMG/cdmg-logo.png?raw=true" />
         </div>
         <div class="col">
             <div>