Volatility namespace rename

[ikelos]

The plugins currently in the repo were designed for a pre-release version of volatility, and would need to be updated to run properly, by changing import volatility to import volatility3 (and similar with from volatility). The framework version number was also clocked back given the shift in namespace, so the _required_framework_version for these plugins would need to be set to (1, 0, 0).