Fix issue #29: Log messages that display errno should display the associated error text instead.

Add error message to socket errors (instead of just errno).

Changes `socketError(..)` output from:

> Failed to connect to server, rc: -1, errno: 113

to:

> Failed to connect to server, rc: -1. Error: 'No route to host' (errno: 113)

which should give some more information to the user.

Fix #29.