* Squashed commit of the following:

commit 5fdd89a8529743f05e84f837f64816f527506ff4
Merge: 9405cba3 90640854
Author: Louis Feng <louis.feng@intel.com>
Date:   Sun Feb 11 10:10:35 2018 -0800

    Merge branch 'master' into louisfeng/NGMX-275

commit 9405cba3c93b9ed7f61e2b7e28c47c5a1f95882a
Author: Louis Feng <louis.feng@intel.com>
Date:   Sun Feb 11 10:03:34 2018 -0800

    refactor with new policy.

commit ee3a1fb007fd9ba7a6b687391381900ad81fbce3
Author: Louis Feng <louis.feng@intel.com>
Date:   Sat Feb 10 23:49:16 2018 -0800

    added scoped emitter util.

commit 0ec93d0f3a62f7ada4aad1242a14ff34670c0512
Author: Louis Feng <louis.feng@intel.com>
Date:   Sat Feb 10 01:10:57 2018 -0800

    refactored common code.

commit 8acb3e10cb0328425a25688fe8f1d485c46a3892
Merge: 1835daf3 8d938e32
Author: Louis Feng <louis.feng@intel.com>
Date:   Fri Feb 9 21:59:55 2018 -0800

    Merge branch 'master' into louisfeng/NGMX-275

commit 1835daf3fe8bfcfa4dae41dc64249c15f0d2550c
Author: Louis Feng <louis.feng@intel.com>
Date:   Fri Feb 9 21:59:35 2018 -0800

    fixed errors.

commit 0eb5b34edc5c2035bf4bd929a467bfbdda231640
Merge: 35422d27 9918436d
Author: Louis Feng <louis.feng@intel.com>
Date:   Fri Feb 9 15:34:14 2018 -0800

    Merge branch 'louisfeng/fix-isnan' into louisfeng/NGMX-275

commit 35422d27b3ddd146bfb97c8bdf70919b411c24fc
Merge: 4ebde727 85a17aeb
Author: Louis Feng <louis.feng@intel.com>
Date:   Fri Feb 9 15:33:56 2018 -0800

    Merge branch 'master' into louisfeng/NGMX-275

commit 4ebde72731c5b82f67362249c6c29b8073c9ec85
Author: Louis Feng <louis.feng@intel.com>
Date:   Fri Feb 9 15:25:00 2018 -0800

    WIP.

commit 40f43c78285ee8003b84a16d1dba78c4a56a479e
Author: Louis Feng <louis.feng@intel.com>
Date:   Thu Feb 8 22:13:21 2018 -0800

    fixed dilation, passing all conv tests, fixed mxnet ngraph missing mkldnn namespace errors.

commit 34bc573f44a15bf39d4e547724c64a31093c2f4e
Author: Louis Feng <louis.feng@intel.com>
Date:   Wed Feb 7 23:42:27 2018 -0800

    fixed padding between ngraph and mkldnn.

commit df63ae6cd8694a6e63c0affa0a5747279ad5dfab
Author: Louis Feng <louis.feng@intel.com>
Date:   Wed Feb 7 23:34:41 2018 -0800

    fixed padding etc.

commit 62a7c8a89b6ddacd22f28c61389f7496482b87d2
Author: Louis Feng <louis.feng@intel.com>
Date:   Wed Feb 7 17:28:13 2018 -0800

    convolution backprop with mkldnn.

* minor changes.

* Fixed test case fail due to missing mkldnn head. Added new mkldnn ops to list of header include check.

* style format.

* rethrow ngraph execption and removed cerr message.

* refactor to keep changes within emitters.

* removed mkldnn util.