Support a cwd='other' argument in the run command

[GoogleCodeExporter]

What steps will reproduce the problem?

1. run('gcc', '-c', 'test.c', cwd='other')

What is the expected output? What do you see instead?

I would expect it to work. Instead, ".deps" gets created in the subdirectory 
and the paths there are wrong.

What version of the product are you using? On what operating system?

1.25 on Linux

Please provide any additional information below.

It seems that fabricate has no support for the "cwd" keyword argument. Adding 
this is fairly trivial, however. The "cwd" keyword argument needs to be passed 
onwards as the first process cwd, instead of the hardcoded '.' that is there 
now.

Original issue reported on code.google.com by [email protected] on 6 Jul 2013 at 5:53