parse sample data in vcf-io-benchmark
use boost::spirit::qi to parse integers in tokenizer
add move constructor to CustomValue

gcc 4.4 requires us to explicitly define the copy constructor as well.
add fromString static method to Vcf::Header
remove unused function CustomValue::setString
add isScalar method to CustomType
add test suite for vcf sample data

previously it was tested through entry, i'll break those tests out soon.