Switch elasticsearch repo cfg to a command.

This switches the elasticsearch repo configuration to be a sudo tee
command with a heredoc, rather than just a file, to make it trivially
copy-pasteable.
Switch devtools repo download to use curl.

curl is available on a minimal CentOS install, wget is not.
Fix missing service start for httpd & memcached.
Don't require a socorro checkout for deploy.sh

This changes the docs to download the latest deploy.sh (since it doesn't
depend on anything from the git repo) and changes deploy.sh to download
the tar.gz to the same directory as the script resides in, rather than
the current PWD. This makes it less error prone when $PWD changes
between invocations.
deploy: Don't fail if there's no system local.py.

This also makes deploy copy an initial local.py into /etc/socorro.
deploy: Only overwrite socorro.tar.gz on success.
Merge pull request #2112 from jorgenpt/setup-docs-improvements

Setup docs improvements