Determine auth URLs more intelligently
Add blank line to output for FileDownloader.

The VcsDownloader outputs a blank line between each dependency:

https://github.com/composer/composer/blob/745dcbce3317f7119575c39cef2cb601f9c5ffcf/src/Composer/Downloader/VcsDownloader.php#L80

This write makes output consistent.
Register plugin only one time when it's present in global and project mode
Fix phpdoc
Option to disable inclusion of hostname in OAuth app name
Update troubeshooting.md to suggest clearing Composer's cache.
added test unlinking directory

#3157
rmdir needs to be used on windows to remove symbolic links to directories
added test removing directory with trailing slash that is symlinked

#3144
#3157
unlinking symlinked directories and trailing slashes

Filesystem::removeDirectory() didn't detect all symlinked directories
properly due to not resolving pathnames with trailing slashes first.

this commit fixes that issue by resolving pathnames with trailing slashes
by removing those in case they are representing a symlinked directory.

#3144

Reference:

 A.4.12 Pathname Resolution - The Open Group Base Specifications Issue 7
 IEEE Std 1003.1, 2013 Edition Section
 <http://pubs.opengroup.org/onlinepubs/9699919799/xrat/V4_xbd_chap04.html>
Add installer events
Clear all the caches
added stof's php inline example from #3190 to doc/articles/scripts.md
Update clear cache command to be more verbose
When $TMPDIR is low on space PHP streams silently fail
Handle incomplete file write to cache
Updated to reflect new tap names for php in OSX homebrew.
Very tiny but necessary edit

To delete `.git` repos of submodules, `rm -rf vendor/**/.git` doesn't work, but `rm -rf vendor/*/*/.git` does
update documentation to work for ZSH or Bash
docu fix (removed dangling "times." introduced by 22afc074a96d27b5462d335e22da893570bf7e87)