Readme formatting fixes
Merge pull request #202 from kot-behemoth/patch-1

Readme formatting fixes
Updated README to reflect fact that version 1.0.0-beta is in fact in the development branch.
Removing the nvd3 development branch note from the header as it was too big.
Updating nvd3 programmatic version number to 1.0.0b
Rebuilding nv.d3.js. Updating README.md to remove note about 1.0.0b being in dev branch.
Updating README.md to unoffically add Opera 15 to list of supported browsers.

I just tested our charts on Opera 15 and they work very nicely.
custom changes to Linechart