extend RNAseq pipeline to support TopHat

Users now have the ability to choose whether to use TopHat or GSnap
as the aligner for the RNAseq pipeline. The reasoning for this
is that TopHat is more widely used program and the user should have the
option change the aligner.

	modified:   scripts/qteller.pl
	modified:   web/LoadExperiment.pl
	modified:   web/tmpl/LoadExperiment.tmpl
generate seperate metadata for the given pipeline

Add `generate_metadata` to return the metadata assocated with the steps
run during the load given the alignment pipeline chosen and whether the
genome has annotations.

	modified:   scripts/qteller.pl