Don't include tag if not needed

[jssuttles]

#43
{
untilTag: {
tag: '',
include: false
}
}
untilTag option now takes object like above or string like before

[yagni]

Is c55297f necessary? You can already tell if a byteArrayParser is big or little endian by comparing it to the dicomParser.bigEndianByteArrayParser and dicomParser.littleEndianByteArrayParser objects directly.

[jssuttles]

Probably didn't need to push that to this pull request, however, if the dicomWriter that I wrote is to understand whether data is to be handled with little endian or big endian without having to look at the data itself, then it's a really nice helper. The dicomWriter, then, doesn't need to require the dicomParser, so that it can compare the parsers.