* refine PADDLE_THROW, test=develop

* refine error msg, test=develop

* refine cuda error, test=develop

* follow comments, test=develop

* fix compile problem, test=develop

* fix bug, test=develop

* improve save and load behaviour, test=develop

* code cleaning, test=develop

* disable check_guards and update_guards in release version, test=develop

* fix compilation issue, test=develop

* add buddy_allocator speed test data, test=develop

* fix compilation issue, test=develop

* fix comment, test=develop

* update function names according to the google C++ style guide, test=develop

* tweak the test data format, test=develop

* move buddy_allocator_test_data to paddle/fluid/testdata, test=develop

* add accessor and mutator for Desc, test=develop

* replace part of PADDLE_ASSERT to PADDLE_ENFORCE

test=develop

* remove unused fallback_alloc_size_

* add unit-test of CUDAPinnedAllocator

test=develop