Initial files
new interfaces
add option to compute U
new tests, SVD interface

Conflicts:
	mllib/src/main/scala/org/apache/spark/mllib/linalg/SVD.scala
fix tests
Documentation, yo
added mllib guide docs

Conflicts:
	docs/mllib-guide.md
SparkPCA example
fix typo

Conflicts:
	docs/mllib-guide.md
fix example
docs
style changes
stylin'
handle missing zeros
Added DenseMatrices, used them throughout for PCA
More docs, camelcasing, fixing examples

Conflicts:
	docs/mllib-guide.md
style changes
compute column sums in place, then broadcast.
Dense Matrix SVD plus tests
documentation