Printing noquoted empty strings in cause attrs is confusing

[Richard Cotton]

Either override print method to display a '.' for empty strings, or stop noquoting, or print like you get in the error msg. Preferably the latter.

[Richard Cotton]

Fixed via commits https://bitbucket.org/richierocks/assertive/commits/2af1f17697c0c68701b17dd89408500f205e4ad1 thorugh to https://bitbucket.org/richierocks/assertive/commits/63006789d74e7d00753120730680c6770b633935