add external links
added compatible windows-linux relative symlinks
fixed double slashes in getRelativePath()
Merge pull request #132 from vs7/master

added compatible windows-linux relative symlinks
try to fix travisCI problem
revert last commit and mark test as skipped
drop support for php versions 5.3 and 5.4
Merge branch 'master' of github.com:magento-hackathon/magento-composer-installer into 3.0
remove core-installer feature

- removing does not break any tests
- is now implemented in github.com/bragento/bragento-composer-installer
remove documentation about the core installer