Randomize temporary env output file name to avoid conflict

Related to #80.
Fallback to Atom's env variables when failed fetching login shell's ones

We should use all the env variables not only HOME.

Related to #80.
Avoid wasteful double linting on launch caused by atom.config.observe

Related to #80.
Update changelog for 0.14.4
Prepare 0.14.4 release
Conform to the change of exit code in SCSSLint 0.26

* https://github.com/yujinakayama/atom-lint/issues/71#issuecomment-50979861
* https://github.com/causes/scss-lint/commit/a5f69c1a1b39bb00aacfdba75fb06f77097fc6a8
Prepare 0.14.5 release
Rename CommandRunner._cachedEnv
Suppress error output in CommandRunner spec
Improve wording in README
Catch only JSON parsing error in RuboCop class
Bump clang-flags dependency and required Atom version

This closes #81.
Prepare 0.15.0 release
Specify pathwatcher dependency to solve incompatibility issue this time

Related to #83.
Prepare 0.15.1 release
Add a comment about runtime color generation in ViolationTooltip
Pass EditorView to ViolationTooltip instead of ViolationView
Extract some logic unrelated to violation in ViolationTooltip
Refactor attachment content handling in Violation
Use modern mark-up in HLint violation attachment