Add proxy support

[mjtko]

In some deployments, Clusterware has to operate behind a web proxy or other restricted access to upstream Internet services.

Parts of the codebase should be enhanced to allow for Clusterware to function under these conditions:

• For wget: /etc/wgetrc is a sledgehammer to fix this, there may be better ways.
• For git: ${cw_ROOT}/opt/git/etc/gitconfig can be updated to state:

[http]
proxy = http://proxyhost:port/

• For s3cmd: action-managed s3cfg files should have proxy settings written into them.
• Job queue processing doesn't use a config file at the moment, so the only way to convince this to work is to create a /root/.s3cfg file containing the proxy settings -- this should be fixed.
• For yum: requires a proxy= line in /etc/yum.conf -- again there may be better ways.
• Create a profile script that sets up proxy settings in user environments, e.g.:

http_proxy=http://proxyhost:port/
https_proxy=$http_proxy
ftp_proxy=$http_proxy
rsync_proxy=$http_proxy
no_proxy="localhost,127.0.0.1,localaddress,.localdomain.com"

• Any other places. :)