add solution to #1454 to troubleshooting

The solution suggested by Seldaek helped to solve the issue.

https://github.com/composer/composer/issues/1454
Added post-autoload-dump script event.
Make Event devMode argument optional (false by default).
Added option to only show available packages

Added the --available (-a) option to the show command to only list
the available packages, similar to the --installed and --platform
options.

Additionally changed the output formatting when limiting the
package result to remove the hierarchy when only one type is being
showed. This facilitates parsing of a list of packages (for example
for shell scripting and completion).
Added option to only show package names

Added the --name-only (-N) option to the show command to only list
package names (and exclude version and description).

This is useful to produce a list of package names to be parsed by
a shell script for example (bash completion comes to mind).
added type check to autoloader fixes #1504
Throw Exception on broken signature

This is related to issue #1562

With a fresh installation of Composer I had the following message:

> The contents of https://packagist.org/p/providers-latest.json do not
match its signature, this is most likely due to a temporary glitch but
could indicate a man-in-the-middle attack.
> Try running composer again and please report it if it still persists.

This was *probably* a temporary glitch, as the error did not appear
again, even after a full reinstallation of all packages.

*However* Composer had no way to differentiate a man-in-the-middle
attack and a temporary glitch. The installation / update did continue
despite the problem and files where installed / updates with no easy
rollback. These files may have been corrupted with malicious code and I
have no way to check they don't.

This is a *serious* security issue.

The code in [ComposerRepository line
434](https://github.com/composer/composer/blob/master/src/Composer/Repos
itory/ComposerRepository.php#L434) states

```php
// TODO throw SecurityException and abort once we are sure this can not
happen accidentally
````

Even if the broken signature may happen in accidentally in a standard
process, if it may be a security issue, we have to abort the procedure,
or at least ask for confirmation to the user. If it helps continuing
despite the temporary glitch, it may be possible to add a command line
switch like `--ignore-signature` to force the process to continue.

Proposed :
Send a RepositorySecurityException instead of the warning, even if this
may happen accidentally
Fix RepositorySecurityException class name
Recommend actual version as constraint with installers. Ref composer/installers#58.
Merge pull request #1592 from shama/faq-installers

Recommend actual version as constraint with installers.
Fix repository test
Fix json manipulator handling of escaped backslashes, fixes #1588
Display SSL errors

`curl -s` not only hides the progress bar, it also hides errors. `-S` makes the errors show up again.
Add curl -sS everywhere
Add test for escape sequences
Update deps
Merge remote-tracking branch 'igorw/patch-5'
Merge remote-tracking branch 'gerryvdm/master'

Conflicts:
	src/Composer/Command/ShowCommand.php
Show proper repo information and not always the default ones
Merge remote-tracking branch 'cmodijk/master'