1.9.8 ggplot2 1.0.0 bugfix, mt enhancement

CHANGES IN VERSION 1.9.8
-------------------------

USER-VISIBLE CHANGES

	- `mt` includes other corrections, FDR by default.

	- Resolves [Issue 59](https://github.com/joey711/phyloseq/issues/59)

CHANGES IN VERSION 1.9.7
-------------------------

BUG FIXES

	- Now requires ggplot2 version 1.0.0

	- Fixes bug in which ggplot 1.0 breaks in a phyloseq vignette 

	- Resolves [Issue 347](https://github.com/joey711/phyloseq/issues/347)