[docs] install update: dependencies, CPU-only, Ubuntu 14.04

- update dependency versions
- document CPU-only build
- add Ubuntu 14.04 details
- include LMDB
- warn about defective CUDA driver series 331.*
link OpenBLAS as blas

OpenBLAS is most easily configured by `update-alternatives` or other
symlink strategies.

See https://github.com/BVLC/caffe/issues/314#issuecomment-40703048
[docs] contact us on webpage
[fix] adding requirements.txt for web_demo. Closes #704
[example] standardize imagenet leveldb names
[docs] announce caffe-users
[example] include image dimensions for oversampling
Merge pull request #825 from shelhamer/mailing-list

Announce caffe-users mailing list
Included cmath in common.hpp to avoid isnan complaints from the xcode compiler
turns out you need using::isnan too
the compiler complains about solver tests using pointers as bool
Solver switching support & implementation of Nesterov's accelerated gradient and AdaGrad
restored vituals in solver.hpp
converted pointers to shared_ptr
fixed solver constructor in train_net.cpp
improved numerical stability for AdaGrad
bugfixes for AdaGrad
Added L1 regularization support for the weights
fixed caffe.proto after a mistaken rebase
Addressed Yangqing's comments