Update src/nl/sense_os/service/commonsense/SenseApi.java

Fixed 2 issues with uploading UTF-8 data. 

 - When no charset is given in the Content-Type header "ISO-8859-1" should be assumed (see http://www.w3.org/Protocols/rfc2616/rfc2616-sec3.html#sec3.7.1). Because we're uploading UTF-8 the charset should be set to UTF-8.

 - The DataOuputStream.write() function only writes the low order 8-bit bytes from the specified string. In other words no UTF-8 (a character can have more than one byte). This fix will resolve this.