Hammer CLI

when there is no log_dir set user is getting the following error:

$hammer
/usr/share/ruby/fileutils.rb:1544:in `path': no implicit conversion of nil into String (TypeError)
from /usr/share/ruby/fileutils.rb:1544:in `block in fu_list'
from /usr/share/ruby/fileutils.rb:1544:in `map'
from /usr/share/ruby/fileutils.rb:1544:in `fu_list'
from /usr/share/ruby/fileutils.rb:199:in `mkdir_p'
from /usr/local/share/gems/gems/hammer_cli-0.0.1/lib/hammer_cli/logger.rb:24:in `<module:Logger>'
from /usr/local/share/gems/gems/hammer_cli-0.0.1/lib/hammer_cli/logger.rb:5:in `<module:HammerCLI>'
from /usr/local/share/gems/gems/hammer_cli-0.0.1/lib/hammer_cli/logger.rb:4:in `<top (required)>'
from /usr/share/rubygems/rubygems/core_ext/kernel_require.rb:51:in `require'

set default to /var/log/foreman/ or ~/.foreman/log

PR #9 https://github.com/theforeman/hammer-cli/pull/9 added
- default log_dir (/var/log/foreamn)
- support for ~ in :log_dir
- suggested to use config template in install instructions