Add a no-interface option to no-inheritance and no-multiple-inheritance

[nfeignon]

In response to Augur bounties: "Prohibit use of multiple inheritance but allow interfaces" and "Prohibit use of inheritance but allow interfaces".

Let me know if there's anything to fix.

[duaraghav8]

@nfeignon I had a discussion about these 2 rules with tinybike. They need to be merged with no-inheritance & no-multiple-inheritance respectively. How this works is:

• We will have no-inheritance that doesn't allow inheritance but does allow interfaces (default setting).
• This rule can be supplied an option to disallow interfaces (inside .soliumrc.json)

  {
  "rules": {
  "security/no-inheritance": ["error", { "no-interface": true }]
  "security/no-multiple-inheritance": ["error", { "no-interface": true }]
  }
  }

  The same applies to no-multiple-inheritance (as seen in above eg)

Can you please augment the changes into the existing rules? Sorry to cause you the trouble, but this approach is much more elegant. NOTE: modifying the existing rules is treated as 2 new rules submitted and bounty awarded accordingly

[nfeignon]

Updated my PR. Let me know if there's anything to fix!

[duaraghav8]

@nfeignon I've requested 2 changes in no-inheritance. They also apply to no-multiple-inheritance. Everything else is good.

[nfeignon]

Updated the PR and rebased :)