Calculate bytes sent by the Python client using byte buffer

[mzarnowski]

For each command, the entire user environment is being send to the server. Any variable in the environment can contain a unicode (e.g. PS1 - a fancy prompt configuration)

Sending messages works as follows:
given buffer buf (a string):

1. calculate the amount of bytes sent - by using len(buf)
2. send the header containing the length of the string message
3. convert string to bytes using bbuf = to_bytes(buf)
4. send bytes from bbuf

The amount of bytes should be calculated using bbuf: (len(bbuf), not len(buf))

[jvican]

Thanks, trusting that this works, I'm merging and I'll add this to the bloop release happening today.