adopt a more stable proxy configuration

adopt proxy configuration as documented by @niq (Nick Kew)

   http://www.apachetutor.org/admin/reverseproxies documents the

This pattern is more resilient to shaky redirects from the backend
This commit fixes #300.
Fix for issue 358. Including apache::mod::proxy and apache::mod::proxy_http so they're available to be used
Merge pull request #360 from bmurt/iss358

Fix for issue #358. Including apache::mod::proxy and apache::mod::proxy_h...
Add conditional <IfModule> directive to alias_module template.
Add 'Timeout' core directive.
Merge pull request #367 from pataquets/add-timeout-parameter

Add 'Timeout' core directive.
Merge pull request #366 from pataquets/add-ifmodule-to-alias

Add conditional <IfModule> directive to alias_module template.
Convert sendfile param to string from bool.

Currently, one would assume that since the default is false, setting `sendfile
=> true` would cause the option to be enabled in httpd.conf, but instead it
writes `sendfile true` which is incorrect.  This makes the usage consistant
with commit a82af5595e1e51961903873b6171bd5e08857d60.  Includes rspec
tests and input validation.
Merge pull request #365 from razorsedge/sendfile

Convert sendfile param to string from bool.
Merge pull request #306 from igalic/proxy_stable

adopt a more stable proxy configuration
Fix invalid variable name in itk mod