Add message attribute to CommandTimeout class so __str__ method returns a
message and not an empty string.

Also add timeout attribute so we have access to the original timeout argument.
Changelog closes #1228
Include error message in task abort exception

Change-Id: I22856d54b3d55663d8f11c8ad7efa9871a744c14
Changelog closes #1213
Account for the fact that some file-like objects may not have a isatty() method.

Conflicts:
	fabric/utils.py
Changelog re #1019, closes #1019, closes #1022, closes #1186
Merge branch '1.9' into 1.10