Merge pull request #2138 from sascha-egerer/feature/add_status_event_scripts

Add pre-status-cmd and post-status-cmd script hooks
Generate an autoload_files.php next to autoload_namespaces.php and autoload_classes.php
Factor the filesCode generation into a separate method.
autoload_files.php should return an array of files, instead of directly including them.
Merge pull request #2139 from donquixote/feature/autoload-files-corrected-1

Feature/autoload files corrected 1
Slightly nicer heredoc in AutoloadGenerator::getIncludePathsFile()
Merge pull request #2141 from donquixote/feature/autoload-generator-heredoc

Slightly nicer heredoc in AutoloadGenerator::getIncludePathsFile()
Merge pull request #2091 from jaypea/archivemanager

cleanup temporary download location when archiving
fix some files mode bug 755->644
Throw exception if the local repository does not contain a package to uninstall
Merge pull request #2151 from bronze1man/pr-file-mode

fix some files mode bug 755->644
[docs] Correct note about require-dev not being installed on install

It's now installed by default.
Merge pull request #2158 from igorw/patch-8

[docs] Correct note about require-dev not being installed on install
Factory uses "prefered-install" configuration when creating
DownloadManager
attach IO to DownloadManager in "package" command
removes hardcoded "prefer-source" in ArchiveManage when calling
DownloadManager
use available $io in archive
https://github.com/composer/composer/pull/2099#pullrequestreviewcomment-5318806
Add IO to proc executor in a few more places to get more debug info out
Only check for the package time if a package is actually installed from source, refs #2096
Realpath hg paths to avoid problems after a chdir, fixes #2096