default backend to lmdb for image conversion and mean computation

lmdb is 10-15% faster than leveldb although it takes ~1.1x the storage.
This is usually irrelevant in prefetching since both are fast enough,
but more important lmdb allows multiple, concurrent reads for training
and evaluation several models on the same data.
switch examples to lmdb (except for custom data loaders)
Merge pull request #1128 from shelhamer/default-db-lmdb

default to lmdb for database storage
Changed "blas" to "openblas"

The change was made because openblas has to be linked as "-lopenblas" and not "-lblas". This caused an error when compiling.
Fixed param order of cv::Size in cv::resize
Merge pull request #1152 from sguada/fix_cv_size_order

Fix param order of cv::Size in cv::resize
Merge pull request #1147 from savy-91/patch-1

Changed "blas" to "openblas"
tweak test case to expose bug.
update HDF5 layer test data.
fix hdf5 data layer bug
Merge pull request #1166 from pluskid/master

bugfix: HDF5 layer reshape bug
[fix] solver indexing of output blobs was incorrect for non-singleton
outputs
Merge pull request #1203 from jeffdonahue/fix-output-blob-indexing

[fix] solver indexing of output blobs was incorrect for non-singleton outputs
Update detect.py

This generator causes an error in detect_windows because it is run twice there.
Better store it as a data structure instead.
Merge pull request #1198 from dbbert/patch-1
[fix] check solver prototxt parsing
Merge pull request #1226 from longjon/check-solver-prototxt

[fix] check solver prototxt parsing
[example] fix data script paths for flickr fine-tuning
[example] add LeNet to MNIST title, fix paths to be from root
[example] re-title LeNet / MNIST heading too