Mark 1.3.x and 1.4.x unmaintained

There are currently no serious fixes in the backlog and 1.5.1 ill get the
fixes.

website/download/download.html

@@ -33,7 +33,7 @@
 <tr><td class="reldate">2015-09-12</td><td class="filename"><a href="duktape-1.3.0.tar.xz">duktape-1.3.0.tar.xz</a></td><td class="description">typed arrays, duk_config.h, module.exports, performance</td><td class="hash">XXX</td></tr>
 <tr><td class="reldate">2015-11-27</td><td class="filename"><a href="duktape-1.3.1.tar.xz">duktape-1.3.1.tar.xz</a></td><td class="description">maintenance release</td><td class="hash">XXX</td></tr>
 <tr><td class="reldate">2016-01-11</td><td class="filename"><a href="duktape-1.3.2.tar.xz">duktape-1.3.2.tar.xz</a></td><td class="description">maintenance release</td><td class="hash">XXX</td></tr>
-<tr><td class="reldate">2016-04-17</td><td class="filename"><a href="duktape-1.3.3.tar.xz">duktape-1.3.3.tar.xz</a></td><td class="description">maintenance release</td><td class="hash">XXX</td></tr>
+<tr><td class="reldate">2016-04-17</td><td class="filename"><a href="duktape-1.3.3.tar.xz">duktape-1.3.3.tar.xz</a></td><td class="description">maintenance release (no longer maintained)</td><td class="hash">XXX</td></tr>
 <tr><td class="reldate">2016-01-10</td><td class="filename"><a href="duktape-1.4.0.tar.xz">duktape-1.4.0.tar.xz</a></td><td class="description">minor fixes and improvements, performance</td><td class="hash">XXX</td></tr>
 <tr><td class="reldate">2016-04-19</td><td class="filename"><a href="duktape-1.4.1.tar.xz">duktape-1.4.1.tar.xz</a></td><td class="description">maintenance release</td><td class="hash">XXX</td></tr>
 <tr><td class="reldate">2016-08-29</td><td class="filename"><a href="duktape-1.4.2.tar.xz">duktape-1.4.2.tar.xz</a></td><td class="description">maintenance release (no longer maintained)</td><td class="hash">XXX</td></tr>