don't fail on non ascii chars

the butler fails on processing a file which contains non ascii chars (e.g. umlauts like a ä is already enough)

production_pinder-butler | '2019-06-05 21:14:06,677:INFO:Processing queue /bot/watchDir/files.que'
production_pinder-butler | '2019-06-05 21:14:06,677:DEBUG:Attempting to acquire lock 140207008908904 on /bot/watchDir/files.que.lock'
production_pinder-butler | '2019-06-05 21:14:06,677:INFO:Lock 140207008908904 acquired on /bot/watchDir/files.que.lock'
production_pinder-butler | '2019-06-05 21:14:06,677:DEBUG:Attempting to release lock 140207008908904 on /bot/watchDir/files.que.lock'
production_pinder-butler | '2019-06-05 21:14:06,677:INFO:Lock 140207008908904 released on /bot/watchDir/files.que.lock'
production_pinder-butler | '2019-06-05 21:14:06,677:DEBUG:Contentfile ['/app/data/1559769146.pro']'
production_pinder-butler | '2019-06-05 21:14:06,677:INFO:Processing new content /bot/watchDir/1559769146.pro'
production_pinder-butler | '2019-06-05 21:14:06,678:DEBUG:Merging /bot/watchDir/1559769146.pro into /bot/repo/content.js file'
production_pinder-butler | Traceback (most recent call last):
production_pinder-butler |   File "/bot/src/main.py", line 59, in <module>
production_pinder-butler |     processQueue()
production_pinder-butler |   File "/bot/src/main.py", line 38, in processQueue
production_pinder-butler |     if pinderButler.processNewContent(filePath, lambda success: success):
production_pinder-butler |   File "/bot/src/PinderButler.py", line 63, in processNewContent
production_pinder-butler |     newContent = f.read()
production_pinder-butler |   File "/usr/lib/python3.6/encodings/ascii.py", line 26, in decode
production_pinder-butler |     return codecs.ascii_decode(input, self.errors)[0]
production_pinder-butler | UnicodeDecodeError: 'ascii' codec can't decode byte 0xc3 in position 303: ordinal not in range(128)

ideally we should fully support UTF-8... we might also face emojis and other special chars...

@jeanggi90 could you look into this?