[MERGE][0.14] Skip tests when 'tools' is not available

[Alexander Belchenko]

Alexander Belchenko has voted +1 (conditional).
Status is now: Conditionally approved
Comment:
Your fix is good enough for me.
Although if you don't satisfied with it we could rework it to explicit 
check presence file setup.py or directory tools in the directory with 
bzr script itself.

For details, see: 
http://bundlebuggy.aaronbentley.com/request/%3C45AF8976.8060506%40arbash-meinel.com%3E