JimB is correct, packages are relative to the import path. There is no capability to import 'absolutely'.
While it is not spelled out specifically in the spec, it does allude to it at https://golang.org/ref/spec#ImportPath:
The interpretation of the ImportPath is implementation-dependent but it is typically a substring of the full file name of the compiled package and may be relative to a repository of installed packages.
There are variations on relative importing and vendoring that might work for you (see GO 1.5 vendoring experiment, now available in 1.6 https://docs.google.com/document/d/1Bz5-UB7g2uPBdOx-rw5t9MxJwkfpx90cqG9AFL0JAYo/edit?pref=2&pli=1)