Set Python-related variables if they're not set

Set a variable we can test for if we have a relatively
modern python interpreter

Change-Id: Iddbd3d857d5ddcb36e3eae45e7ada96a64682bc8
Reviewed-on: http://review.couchbase.org/29291
Reviewed-by: Trond Norbye <trond.norbye@gmail.com>
Tested-by: Trond Norbye <trond.norbye@gmail.com>
Look for libcurl_imp as well

Change-Id: I952d06bce9bc31f369be645c8588f9d3b95d9dbc
Reviewed-on: http://review.couchbase.org/29293
Reviewed-by: Trond Norbye <trond.norbye@gmail.com>
Tested-by: Trond Norbye <trond.norbye@gmail.com>
Build dependencies by using cmake in a separate dir

Change-Id: I1aafa1aa55c20aa35c6eb43f7fe36bf72ad0debe
Reviewed-on: http://review.couchbase.org/29292
Reviewed-by: Trond Norbye <trond.norbye@gmail.com>
Tested-by: Trond Norbye <trond.norbye@gmail.com>
Try to copy stuff to other dirs

Change-Id: I16f33c2e226a44f951cbdca448a7163bf8eaec5f