[split] Move balias plugin to oh-my-fish/plugin-balias

https://github.com/oh-my-fish/plugin-balias

plugins/balias/README.md

-# A better alias provide completion
-
-Use `balias` instead of `alias`,you can get same completion meanwhile you set  alias.
-
-# Example
-
-```
-balias apti 'sudo apt-get install'
-balias gc   'git checkout'
-```
-
-Then,you will get
-
-![apti](http://www.geekpics.net/images/2014/08/23/TJn6kfBY.png)
-
-![gc](http://www.geekpics.net/images/2014/08/23/655x76xcPJolvxqra.png.pagespeed.ic.4S9hgPfZ53.png)

plugins/balias/balias.fish

-function balias --argument alias command
-  eval 'alias $alias $command'
-  if expr $command : '^sudo '>/dev/null
-    set command (echo "$command" | cut -c6-)
-  end
-  complete -c $alias -xa "(
-    set -l cmd (commandline -pc | sed -e 's/^ *\S\+ *//' );
-    complete -C\"$command \$cmd\";
-  )"
-end

plugins/balias/balias.spec.fish

-import plugins/fish-spec
-import plugins/balias
-
-function describe_library -d "balias: better-alias"
-
-  function after_all
-    functions -e changedir
-    functions -e ls_as_root
-  end
-
-  function it_doesnt_fail
-    balias changedir cd
-    expect $status --to-equal 0
-  end
-
-  function it_defines_an_alias
-    balias changedir cd
-    set -l ignore_output (functions changedir)
-    expect $status --to-equal 0
-  end
-
-  function you_can_use_the_alias
-    mkdir testdir
-    changedir testdir
-    expect test $status --to-be-true
-    cd ..
-    rmdir testdir
-  end
-
-  function it_chops_off_sudo
-    balias ls_as_root 'sudo ls'
-    expect test $status --to-be-true
-  end
-end
-
-spec.run $argv