Suggest, not require Magento Composer Installer

Additionally removed repositories section as it is not needed any longer.

Refrences:

- https://github.com/magento-hackathon/magento-composer-installer/blob/master/doc/FAQ.md
- https://getcomposer.org/doc/04-schema.md#suggest
Merge pull request #31 from tkdb/patch-1

Suggest, not require Magento Composer Installer
Merge pull request #36 from firegento/master

Update composer.json
Fixed bug in require path for GELF (Graylog2)
require_once 'lib/Graylog2-gelf-php/...' is not correct because the Magento root is not in the include_path.
The directory "lib" is in the include_path, so removing it fixes this problem.
The problem occurred when you ran a Magento script which is not in the Magento root, for example a shell script.
Merge pull request #39 from jeroenvermeulen/bugfix_gelf_require_path

Fixed bug in require path for GELF (Graylog2)
[FEATURE] Added delete option to error log grid.

When you log entries to the database, you can (multi-)select entries and delete them from the grid.
Merge pull request #40 from mzeis/develop

[FEATURE] Added delete option to error log grid.
Remove shadowing of Db class instance variables

The instance variables $_db, $_table, and $_columnMap of the Zend_Log_Writer_Db class were redeclared in the FireGento_Logger_Model_Db class with a different visibility. This resulted in the following PHP errors:

    PHP Fatal error:  Access level to FireGento_Logger_Model_Db::$_db must be protected (as in class Zend_Log_Writer_Db) or weaker in /MAGENTO_ROOT/app/code/community/FireGento/Logger/Model/Db.php on line 29
    PHP Fatal error:  Access level to FireGento_Logger_Model_Db::$_table must be protected (as in class Zend_Log_Writer_Db) or weaker in /MAGENTO_ROOT/app/code/community/FireGento/Logger/Model/Db.php on line 29
    PHP Fatal error:  Access level to FireGento_Logger_Model_Db::$_columnMap must be protected (as in class Zend_Log_Writer_Db) or weaker in /MAGENTO_ROOT/app/code/community/FireGento/Logger/Model/Db.php on line 29

These errors can be resolved by changing the visibility of the instance variables from private to public.

However, there is no need to redeclare the instance variables, so I have removed them.
Merge pull request #44 from aadmathijssen/patch-2

Remove shadowing of Db class instance variables
[feature] Sendmail Transport

Allow to use Sendmail Transport next to SMTP Transport.
Merge pull request #41 from ho-nl/develop

Logging to loggly over UDP.
Merge pull request #47 from tkdb/patch-4

[feature] Sendmail Transport
Fix Port on logger
Include paths
Merge pull request #48 from ho-nl/include-paths

Proper include paths
Merge branch 'develop-upstream' into develop