KSPSetPostSolve: doc fix (bad copy/paste)
manual: developers manual has a citation, thus needs bibtex
features: remove release reference from gpus/threads features webpages
cuda/threadcomm: configure print message to use petsc-dev [when using release]
version: switch over from using PETSC_VERSION_PATCH to PETSC_VERSION_SUBMINOR
i.e 3.4 release would have tarballs with names 3.4.0, 3.4.1 3.4.2 etc

Also stop using PETSC_VERSION_PATCH_DATE - but use:
PETSC_RELEASE_DATE: corresponding to release of 3.4, 3.5 etc
PETSC_VERSION_DATE: correspond to patch releases 3.4.0, 3.4.1 3.4.2 etc.

Also fix release/build scripts to work with the new naming scheme.
rebuildtar: update websnapshot when a new release/patch tarball is created
petsc-3.4: set release strings
dev: revert master back to dev by resetting PETSC_VERSION_RELEASE
and reverting 408b84210f4204d220c33572b1c41f435c302dbf