Fix quotation marks that break occurrence file format

[mikkohei13]

In citable data download occurrence.txt file, if record contains a quotation mark, the file cannot be read correctly. I presume e.g. Python csv reader expects a field starting with quotation mark continues until the next quotation mark.

Example records having quotation marks in notes field:

http://tun.fi/JX.785237
http://tun.fi/JX.786251
http://tun.fi/JX.791980
http://tun.fi/JX.792780

Example download with single record: http://tun.fi/HBF.115061

Expected Behaviour

Quotation marks should be escaped in a standardized way.