Version bump to 1.5.3 and changelog update

Author: kpaulisse

.version

@@ -1 +1 @@
-1.5.2
+1.5.3

doc/CHANGELOG.md

@@ -8,6 +8,14 @@
 </tr>
 </thead><tbody>
 
+<tr valign=top>
+<td>1.5.3</td>
+<td>2018-03-05</td>
+<td>
+<li><a href="https://github.com/github/octocatalog-diff/pull/176">#176</a>: (Enhancement) Normalize file resource titles in reference checks</li>
+</td>
+</tr>
+
 <tr valign=top>
 <td>1.5.2</td>
 <td>2017-12-19</td>