Added asyncExec call to MRTask2 intended to be used for non-blocking task invocation (either using continuation/callback style or do not wait for the results at all).

The functionality is basically the same as of dfork call, except the invoked task will run at the same priority level as the calling thread or min_priority if called outside of FJ framework (whereas dfork automatically increases the priority level to avoid deadlock).

Adapted GLM2 (and Parse2) to use this call instead of dfork so that every GLM2 iteration runs at the same priority level (GLM2 launches iterations from FJ thread but uses continuation style callback and not blocking, so there is no risk of deadlock).
Merge remote-tracking branch 'origin/master'
Sparse chunk update.

Added CXIChunk for sparse integer: contains 2,4 or 8 byte values run-length encoded with skip (row-id) having 2 or 4 bytes.
Added CX0Chunk - subclass of CXIChunk specialized for binary sparse vectors with no NAs (contains only row-ids, no values).
Added CXDChunk - subclass of CXIChunk for sparse floats (values always encoded as Doubles)
Removed CX2Chunk - replaced by CXIChunk.

Updated NewChunk to store numbers as sparse by default (added _id array containing row-ids of non-zero elements and not storing zeros).
Update of the  sparse chunks.
Merge branch 'master' of github.com:0xdata/h2o

Conflicts:
	src/main/java/water/MRTask2.java
	src/main/java/water/api/Inspect2.java
increase some timeouts, better msg on missing link
Merge branch 'master' of github.com:0xdata/h2o
hidden layer size must be > 0
Fix for PUB-298. Correct typo in h2o.__clearLogs. Add a Runit test for logging R POST commands and JSON errors.
Added SparseTest for testing of sparse chunks- compression and get/set and get-with-skip-count(iteration only over non-zeros)
Merge branch 'master' of github.com:0xdata/h2o
Progress on PUB-524. Simple implementation of Naive Bayes hooked into R. Currently, can only specify categorical datasets with no NAs. Laplace parameter controls smoothing.
Sparse chunks update.
Merge branch 'master' of github.com:0xdata/h2o
try some basic repeating stuff
Merge branch 'master' of https://github.com/0xdata/h2o
pushing from sm land
Merge branch 'master' of github.com:0xdata/h2o
1) tiny Exec2 fix: ASTassign was missing -1 on row and col.
2) related change: Vec.set() will now close chunks immediately after EACH write. and so repeated calls to Vec.set() will be SLOW.That's because when invoking Vec.set(i,d), nobody holds a reference to the underlying chunk which should get closed when done with updating the it. Vec could keep the ref. to the last modified chunk, but I think it would be problematic (would have to be transient so it would get dropped by cleaner and so on).
Merge branch 'master' of github.com:0xdata/h2o