[freeze break request] make collectd_apache a default of the apache role.

[Ricky Elrod]

We have a lot of app servers where collectd_apache isn't set (presumably
people just forgot to set it). So we haven't been graphing apache
metrics for those app servers. :(

I'd like to propose just making it a default of the apache role.

I tested this on wiki01.stg in 8f182ff510fef867fb1febd7afb51e263251760b
and 74ad22a53d1230633b2bb284bcea3e494c018f59, with success.

Patch follows.

commit 71031420b5713aae175a1761a4db932b08bdf0b9
Author: Ricky Elrod <codeblock(a)fedoraproject.org&gt;
Date:   Mon May 25 04:22:52 2015 +0000

    Test defining collectd_apache in the apache role.

    Signed-off-by: Ricky Elrod <codeblock(a)fedoraproject.org&gt;

diff --git a/roles/apache/defaults/main.yml b/roles/apache/defaults/main.yml
new file mode 100644
index 0000000..372da7b
--- /dev/null
+++ b/roles/apache/defaults/main.yml
@@ -0,0 +1,2 @@
+---
+collectd_apache: true