Various changes made to the module about findtbb HOT 3 CLOSED

I am sorry, but I left a mistake in the code. On line 163, the environment 
variable CPATH shouldn't be passed using variable expansion (doesn't work when 
the variable contains multiple directories) but instead should be passed as ENV 
CPATH.

Correct line 163:
    PATHS ${TBB_INC_SEARCH_DIR} ENV CPATH

I also added handling of debug libraries being in separate directories from the 
release libraries, as is the case when building TBB from source. I also pasted 
the MIT license with the author's name and last year of edit for use in other 
projects.

Thanks!
Included in r36.