Handle env variables with space

Hi there,

I was trying to set a env variable with `octo config:set VARIABLE "somename with space"` and I noticed it was dropping the content after the space, due to bash word splitting on the arguments of set.

To test I used

```bash
octo config:set repo/A_VAR "with spaces"
octo config:get repo/A_VAR
octo config:env

octo start repo
octo restart repo
```
Those changes were required to bypass the bash's quoting inside command expansions.
`$RUN_OPTIONS` would be quoted like `-e 'VAR1="test" VAR2="another test"'` and it would treat all the single-quoted text as one argument for the `-e` parameter.
Using `echo|xargs` we can expand the values of the variables and pass them expanded as arguments