Adds MountSettings

With MountSettings a user is able to specify a list of known
usernames/hosts configurations with ports and private ssh keys.

The settings are stored as a [MountSettings] value in a
~/.vadosettings file.

If the file is absent or vado has failed to read it then the settings
are defaulted to standart vagrant ones.
Making Vado compile with base 4.5
Oops, now it should compile
This time it should really work
Merge pull request #1 from co-dan/vadosettings

Adds MountSettings