implement tile sharing for simple maps which use distarray _tile_mapper
add tile_sharing test
Merge branch 'master' of github.com:spartan-array/spartan

Conflicts:
	spartan/expr/transpose.py
add region_map which supports mapping over a region of an array. For
those tiles which are not in the region, reuse the tiles of the original
array.
Merge pull request #94 from fegin/from_file_parallel

Add from_file_parallel() to support load files from workers.
add a new distributed SVM SDCA algorithm which has good scalability
Merge branch 'master' of github.com:MaggieQi/spartan
Merge pull request #100 from fegin/master

Remove partial_map().
add cholesky matrix decomposition
rename disdca_svm
reduce the map operations in each iteration in cholesky
rename SealArray to SealedArray
remove with_array and with_ex parameters from fn_kw of region_map
change comments of fn parameter in region_map
Merge pull request #101 from MaggieQi/cholesky

Add disdca_svm and cholesky into examples
make rpc faster in python, using ZMQIOLoop to poll message in future.wait function
minor changes, fix the bug in remove_handler
add rpc test
change all the loop to event_loop
a bunch of changes according to code review
close serversocket when the loop ends. remove setupclass and teardownclass method in perf test
use poller inside future instead of loop to control the timeout. a bunch of other changes according the code review