CB-11316 windows: Added content-type for files
CB-11316 windows: Added content-type for files

- added Content-Type header for each file in the multipart upload

 This closes #149

purplecabbage/cordova-plugin-file-transfer,bcalvez/cordova-plugin-file-transfer,starquake/cordova-plugin-file-transfer,alsorokin/cordova-plugin-file-transfer,alsorokin/cordova-plugin-file-transfer,purplecabbage/cordova-plugin-file-transfer,apache/cordova-plugin-file-transfer,nixplay/cordova-plugin-file-transfer,purplecabbage/cordova-plugin-file-transfer,GenusAS/cordova-plugin-file-transfer,starquake/cordova-plugin-file-transfer,nixplay/cordova-plugin-file-transfer,GenusAS/cordova-plugin-file-transfer,nixplay/cordova-plugin-file-transfer,GenusAS/cordova-plugin-file-transfer,apache/cordova-plugin-file-transfer,alsorokin/cordova-plugin-file-transfer,starquake/cordova-plugin-file-transfer,nixplay/cordova-plugin-file-transfer,purplecabbage/cordova-plugin-file-transfer,starquake/cordova-plugin-file-transfer,bcalvez/cordova-plugin-file-transfer,GenusAS/cordova-plugin-file-transfer,alsorokin/cordova-plugin-file-transfer