Fixes text_response == False for Binary attachments
reorganize decoding in __request to avoid decoding errors for messages with
binary content
test object existance in method get_{ticket|user|links|queue}
test object existance for get_attachment*, get_*history methods and code cleanup

- simplify line spliting and searching for more readable code
- reveal exceptions instead of hiding them
fix search with empty result set or invalid custom query
add test for search with empty result
bump version to 1.0.7