fix codec enumeration (in README)

Upon further inspection of the Blosc source code the changes made to the header
README in 8707b4c15b9ee2d553937c17a3c4e78c7fd87738 must be reverted, my bad. As
it turns out, there is now one set of integers used internally by blosc as
arguments to compress and another that is actually used to identify the codec
in the header. I presume that since LZ4 and LZ4HC have the same decompressor,
the same integer (namely ``1``) is used for both. Updated the docs to account
for that.

Also, it turns out that the field that was previously used for the version of
the blosclz is now more general and stores the version of the codec used.
Updated the README to reflect that change.
Updated to LZ4 r113
Updated references to the new project site in docs
versionlz in blosc_buffer_versions() returns the version for LZ internal compressor
Merge pull request #45 from esc/fix_readme

fix codec enumeration (in README)