fixed find() to match only descendant elements

This is the correct jQuery compatible implementation , which I have changed in 0.14 to also match root nodes, my bad.
Also fixed tests that relied on that wrong find() behavior.
Checking in changes prior to tagging of version 0.20.

Changelog diff is:

diff --git a/Changes b/Changes
index af4c265..b5dbcd0 100644
--- a/Changes
+++ b/Changes
@@ -2,6 +2,14 @@ Revision history for Perl extension Web::Query

 {{$NEXT}}

+0.20 2013-05-13T22:51:02Z
+
+    - improved documentation
+    - fixed find() to match only descendant elements
+      This is the correct jQuery compatible implementation, which I have changed in 0.14 to also match root nodes, my bad.
+    - fixed tests that relied on that wrong find() behavior.
+      (cafe01)
+
 0.19 2013-05-12T18:19:57Z

     - implemented contents() jQuery-compatible method