BLD: Don't hard-code path for building notebooks. Closes #1249
_spg_optim returns history of objective function values
Merge pull request #1854 from jseabold/fix-path

BLD: Don't hard-code path for building notebooks. Closes #1249
Merge pull request #1856 from kshedden/cor_nearest_maint2

REF/TST _spg_optim returns history of objective function values
TST: disable test failing with scipy 0.14.0