Suspend does not pause execution

[knoellle]

According to both the readme here and the keybind help within viddy, pressing the s key should pause command execution.
However, this is not the case and only the shown output is kept from updating.

Steps to reproduce

• Open two terminals
• In the first run viddy "date | tee /tmp/date"
• In the second run viddy "cat /tmp/date"
• Press s in the first to "suspend execution"
• Watch the file content keep updating in the second terminal but not in the first.

Affected Version

$ viddy -v
viddy version: 0.3.7

[sachaos]

@knoellle I've fixed this issue by #108