nan.h: add NAN_INDEX_* macros

They compliment the NAN_PROPERTY_* macros, but are the
"indexed" property variants.
README: document the NAN_INDEX_* macros
README: more future-proof installation instructions

Don't need to update the version number every release this way
simplify the "include_dirs" binding code

Now it simply uses the output of require('nan')...

The old command is really verbose. It's time to consolidate it
into a bundled node script. Our users will thank us.
test: utilize the new bindings code for tests

This way we ensure that our bundled bindings code works via the tests.
remove the .index.js file

No longer used...
test: fix whitespace
Merge branch 'update/bindings-improvements' of https://github.com/TooTallNate/nan into 0.5.0-wip
first-pass at changelog for 0.5.0
added @TooTallNate to contribs list
formatting adjustments
s/build/rebuild
remove superfluous commas
@0.5.0