THRIFT-3515 Python 2.6 compatibility and test on CI

This closes #766
diff --git a/configure.ac b/configure.ac
index 27299b4..141b542 100755
--- a/configure.ac
+++ b/configure.ac
@@ -277,7 +277,7 @@
 AX_THRIFT_LIB(python, [Python], yes)
 if test "$with_python" = "yes";  then
   AC_PATH_PROG([TRIAL], [trial])
-  AM_PATH_PYTHON(2.4,, :)
+  AM_PATH_PYTHON(2.6,, :)
   if test -n "$TRIAL" && test "x$PYTHON" != "x" && test "x$PYTHON" != "x:" ; then
     have_python="yes"
   fi