Update to release candidate alpha for 5.1
Update version
Merge pull request #34 from clawpack/5.1-rc-alpha

Update to release candidate alpha for 5.1
Redirect stdout to a file install.log during install to avoid all that
output to the screen.  Fixes
https://github.com/clawpack/pyclaw/issues/338.
Ensure that stdout is restored if something goes wrong during install.
Merge pull request #35 from ketch/redirect_stdout

Redirect stdout to a file install.log during install to avoid all that output to the screen