added should that was missing from one spec's assertion
Merge pull request #136 from cjfuller/missing_should

added should that was missing from one yale spec's assertion
specs for SVD revised and refreshed.
Merge branch 'master' of https://github.com/SciRuby/nmatrix

Conflicts:
	lib/nmatrix/math.rb
Integrated @ryanmt's #138, updated History and README with stuff I
forgot; changed optimization to -O2.