publish: Add warning if aragon app solidity code initializes any global variable

[izqui]

Because of our use of Proxies, child contracts won't initialize global variables when created. In case an app being published does this, we should at least warn the developer.

contract MyFancyApp is App {
  uint initialState = 1;
}

In the above example, when used behind a proxy, initialState will be 0, even though the expectation reading the code is that it will be 1.

We should encourage the developer to make it something like:

contract MyFancyApp is App {
  uint initialState;

  function initialize() onlyInit { initialState = 1; }
}

Edit: this should apply to logic in constructors too

[izqui]

This should also make it in the documentation too

[onbjerg]

Should be fairly simple to do with solidity-parser. Obviously constants are excluded as they're not written to storage.

For the docs I think an illustration would be helpful. Storage is initialized, but just not for the proxy, which is the storage we care about.