Added lib/partition.js

Now you can get a block address range restricted
block device partition, to pass on to file system drivers and the like
Updated lib/partition: Added LBA bounding to zero

Now .readLBA( 0, 1, null, cb ) will read the first block of the
partition, instead of erroring because of OOB addresses
Updated lib/blockdevice: descriptive prop names

- Renamed .hpt -> .headsPerTrack
- Renamed .spt -> .sectorsPerTrack
Updated lib/blockdevice: Removed non-enum .fs

Removed "Make 'this.fs' non-enumerable" - was only used for cleaner output
during eyeballing
Updated package.json: Version 0.2.0
Added automatic block size detection on open()

Block size detection will now kick off during open(),
if no blockSize has been set.
Merge branch 'master' of https://github.com/jhermsmeier/node-blockdevice