travis: Remove node 0.8, add node 0.10

Travis is failing on two accounts:

* "Error: No compatible version found: minimatch@'^0.3.0'"
  (because the version of npm that shipped with 0.8 doesn't
  support ^

* npm WARN engine stringify-object@0.1.8: wanted: {"node":">=0.10.0"}
  (current: {"node":"v0.8.26","npm":"1.2.30"})
  npm WARN engine has-color@0.1.7: wanted: {"node":">=0.10.0"}
  (current: {"node":"v0.8.26","npm":"1.2.30"})
  npm WARN engine configstore@0.2.3: wanted: {"node":">=0.10.0"}
  (current: {"node":"v0.8.26","npm":"1.2.30"})
  npm WARN engine object-assign@0.1.2: wanted: {"node":">=0.10.0"}
  (current: {"node":"v0.8.26","npm":"1.2.30"})

Closes gh-1258