Add S3 plugin and dependencies

Use composer to download and manage dependencies
Implement blocksize for S3
s3: Copy password on save (if not set)
ldap: Fixup path for PEAR includes
Add `hydrate` command for non-phar users
No implied update of dependencies when building
Merge pull request #11 from greezybacon/feature/s3

Attachment storage in Amazon S3

Reviewed-By: Peter Rotich <peter@osticket.com>