Don't query chain in Signer, use Redux isTest

[jacogr]

No functionality changed, but allows me to break up the Signer changes into smaller chunks.

This one (1 of n) gets rids of the uneeded queries for chain in the Signer. We have the information available on Redux, so no need to make extra queries for each component needing the information. As a bonus the chain === 'testnet' || chain === 'morden' change is now only done in one place in the UI, so it cleans up the codebase.

In short: don't query for chain per component and pass it along the chain, use the global state that indicates whether we are on the testnet or not.

Closes https://github.com/ethcore/parity/issues/3522

[coveralls]

Coverage decreased (-0.02%) to 85.971% when pulling 1686d23 on jg-signer-api-queries into 51012d1 on master.

[coveralls]

Coverage decreased (-0.03%) to 85.965% when pulling 4498fd5 on jg-signer-api-queries into 51012d1 on master.

[ngotchac]

Might want to change src/dapps/basiccoin/services.js L108 and src/redux/providers/statusReducer.js L34 from morden to testnet