error on LDA Julia 0.4

Hi I was trying to use the lsa function but it gives an error because svd doesn't seem to support sparse matrices

```
corpus = Corpus(docs)
update_lexicon!(corpus)
dtmat = DocumentTermMatrix(corpus)
lda(dtmat)
```

ERROR: `svdfact` has no method matching svdfact(::SparseMatrixCSC{Float64,Int64})
