Cleans up some local dev specific changes
Adds options for phantomjs and fail_silently. The phantomjs option
defaults to the default phantom executable (which is defined in the
    phantom model). The fail_silently option specifies whether
exceptions should be explicitly raised or not.
Removes bang methods from phantom class to simplify operations.
Exceptions are raised if the fail_silently option passed to an instance.
Modifies constructor to accept an explicitly designated executable - if
this is not specified defaults to the systemwide one. Adds a function
that defines the default phantomjs location. Updates specs.
Updates readme