Handle errors of category 1XXX and 2XXX
Handle errors of category 3XXX, 7XXX and 9XXX
Added a 7digital base exception
Simplify guzzle exception handling
Merge branch 'master' into feature/error-handling

Conflicts:
	spec/SevenDigital/Service/Release.php
Prevent 7digital error handling when content is not xml
Merge pull request #1 from gquemener/feature/error-handling

Error handling