Fix imports and general cleanup

· Import from compat what comes from compat. Yes, some names are available in utils too, but that's an implementation detail.
· Use _match_id consistently whenever possible
· Fix some outdated tests
· Use consistent valid URL (always match the whole protocol, no ^ at start required)
· Use modern test definitions

youtube_dl/extractor/photobucket.py

@@ -4,16 +4,17 @@ import json
 import re
 
 from .common import InfoExtractor
-from ..utils import compat_urllib_parse
+from ..compat import compat_urllib_parse
 
 
 class PhotobucketIE(InfoExtractor):
     _VALID_URL = r'http://(?:[a-z0-9]+\.)?photobucket\.com/.*(([\?\&]current=)|_)(?P<id>.*)\.(?P<ext>(flv)|(mp4))'
     _TEST = {
         'url': 'http://media.photobucket.com/user/rachaneronas/media/TiredofLinkBuildingTryBacklinkMyDomaincom_zpsc0c3b9fa.mp4.html?filters[term]=search&filters[primary]=videos&filters[secondary]=images&sort=1&o=0',
-        'file': 'zpsc0c3b9fa.mp4',
         'md5': '7dabfb92b0a31f6c16cebc0f8e60ff99',
         'info_dict': {
+            'id': 'zpsc0c3b9fa',
+            'ext': 'mp4',
             'timestamp': 1367669341,
             'upload_date': '20130504',
             'uploader': 'rachaneronas',