Update list of rubies to test under travis

Also explicitly add 1.8 rubies to provide a nice upgrade path for
potential users!
Whitespace
Set durable rspec options
Gitignore /tmp and ignore repo relative root
Remove yard group from Guardfile for lower dev cycle latency
Do not include acceptance specs in dev cycle

Acceptance specs should only be run on ci or debugging. Will reactivate
them later via ENV variable or something.
Replace unneded block capture with yield
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