Fixes install --github so it append README.md

- Before it replaced the README.md file with new content, now its
append content in a more proper manner. If no README.md exists its
still created.
- .localeapp was sometimes injected without space on the previous
.gitignore key, now it ensure newline.
Merge pull request #152 from futhr/feature/append-readme

Fixes install --github so it append README.md
Update deprecated File.exists?
Fixed problem with line ending in three dots "...", in https://github.com/Locale/localeapp/issues/91 , reverts
Update Changelog for version 0.8.0
Major bump to 0.8.0
Lock rspec to < 3 so tests pass.

RSpec 3.0.0 stable has been released.
Ensure it do not fallback to rspec 1.3.2

< 3 worked perfect before 3.0.0 stable
Merge branch 'master' into exception_sending_blacklist

Conflicts:
	CHANGELOG.md