Allow specifying --installation-id in esrally install

[b-deam]

With this commit we allow users to specify a custom installation id when
invoking the install subcommand, allowing us to control the directory
artifacts are installed into.

Example:

$ esrally install --quiet  --installation-id testing --distribution-version=8.5.2 --node-name="rally-node-0" --network-host="127.0.0.1" --http-port=39200 --master-nodes="rally-node-0" --seed-hosts="127.0.0.1:39300" 
{
  "installation-id": "testing"
}
$ ls ~/.rally/benchmarks/races/testing 
node-config.json  rally-node-0/

[michaelbaamonde]

Nice! This is useful. LGTM.