Testsuite updates and fixes for recently added features.

Testsuite updates and fixes for recently added features.

1. Found bug in 'redundant log' implementation that caused
   problems when converting a linear that spanned multiple
   devices to a mirror (wasn't checking for NULL value of
   provided parameter in _alloc_parallel_area)

2. Testsuite was failing to perform tests when 'not' modifier
   was used.  This allowed a couple issues to slip through.
   Added a 'not_sh' modifier that negates tests performed by
   functions defined in the shell source file.

3. Was initializing a variable to far down, which cause
   previously set value to be overridden.  (This was the
   result of the collision of the "redundant log" and
   lvconvert fix patches.)