Squashed 'tests/files/' changes from 15ce2ab..05fe945

05fe945 Added another pow test
7cf2f6b uncle header with block number = 1
d65c7a3 Merge remote-tracking branch 'origin/PoC9' into PoC9
8e05ce5 uncle tests
7c8f2b4 Merge branch 'PoC9' of github.com:ethereum/tests into PoC9
83d1f4d fixed

git-subtree-dir: tests/files
git-subtree-split: 05fe94507b92dbfbfe8c198df33160eaaf9e87fc