[RELEASE] v0.8 Release (Last release before NNVM refactor (apache#4409)

* [RELEASE] v0.8 Release (Last release before NNVM refactor

* fix

Fix css (apache#3617)

* Fix navigation bar issues

* Small fix

* .DS_Store banished!

* Fix for very small width device

* Small fix

* Reduce banner title font size for small screen

* Fix section-tout disorder

* Rearrange the position of collaborators

Fix a typo include/symbolic.h (apache#2281)

[RELASE] tag 0.7 release (apache#2247)

Merge pull request apache#1894 from mli/master

[docs] bugfix for the search form

Merge pull request apache#1680 from thirdwing/master

[R] added a verbose option to `mx.mlp` in R package. close apache#1608

Merge pull request apache#1580 from linmx0130/master

add AdaGrad optimizer in python, a revised version

Merge pull request apache#1544 from hjk41/master

include stdint.h in c_api.h since uint64_t is not defined

Merge pull request apache#1515 from rupeshs/patch-1

Update readme

Merge pull request apache#1481 from piiswrong/master

fix cudnn layers destruction