do not call schema converter to generate projected schema when the projectionFilterStrubg or projectionSchemaStr is specified
remove unused code
make ParquetFileWriter throw IOException in invalid state case
Merge pull request #367 from Parquet/ioexception

make ParquetFileWriter throw IOException in invalid state case
Merge pull request #366 from Parquet/avoid_convert_thrift_scrooge_class_when_projection_is_not_specified

do not call schema converter to generate projected schema when projection is not set