Fix readsafely in JLD00 on v0.3

This was motivated by the SubArray fix in JLDArchives
Switch to Compat to address ifloor deprecation in julia 0.4
Improve the init structure

This takes steps towards precompilation, but it isn't there yet
Check ccall return value in h5p_set_blosc
Blosc: run cfunction as part of registration
Fix a JLD __init__ problem