Merge pull request #3 from spartan-array/master

merge from the spartan-array:master
add nearest neighbors
correct the comments
* add svm into examples
* add np.norm, np.diag, np.square, inc_vec, np.multiply ... support in buildins
* add test_serialization for local serialization test
Merge branch 'master' of github.com:spartan-array/spartan
Merge pull request #62 from EasonLiao/sklearn_knn

add nearest neighbors
remove assert dep is not list or dict
* add some documents on the svm and builtins
change svm.train and svm.new_train to svm.fit in test_svm
Improve generation of 'graphviz' data.

Don't add uninformative `CollectionExpr` entries to the graph.
Don't add a node more than once.
Use a prettier label for graph nodes if available.
Update reduce.py
* remove register_blobs, get_worker_scores, get_worker_for_reload from
 blob_ctx and core
* change the array reference in master to weakref
get rid of inc_vec and _inc_mapper
Merge pull request #65 from MaggieQi/master

add svm example and some numpy function support
Merge pull request #66 from spartan-array/fix-dot

Improve generation of 'graphviz' data.
Check relation between new extents and old extents to prevent unnecessary distarray creation.
Split compute_splits() into tree functions, good_tile_shape(), compute_splits() and compute_extents().
Refeine reshape.py, eliminate repeated or redundent code.
Merge remote-tracking branch 'upstream/master'
Use master.get().