Implement redux logic for switching active token - closes #1947

[osvaldovega]

What issue have I solved?

-- #1947

How have I implemented/fixed it?

This PR includes the following changes.

Added service actions, reducer and api service file.
Added settings middleware.

The intention of these files are for check/retrieve every time the token (LSK, BTC) switch change the settings of token to properly set the active one and after that retrieve the prices for BTC and LSK.
After the prices are retrieved these will be store in the service reducer where the application can get the the values and dynamics fees for BTC.

How has this been tested?

For test this I had to call the action creator pricesRetrieved from the service action file and see how update/retrieve the prices for the tokens for this the service reducer must be check and see how that get updated from.

service: {
  priceTicker: { BTC: {}, LSK: {} },
  dynamicFees: {},
}

to

service: {
  priceTicker: {
      BTC: { LSK: <value>, USD: <value>, EU: <value>, ... },
      LSK: { BTC: <value>, USD: <value>, EU: <value>, ... },
  },
  dynamicFees: {},
}

This PR is just for the add the functionality and needs to be tested as a whole once the BTC be available in the UI with the switcher.

Review checklist

• The PR follows our Test guide
• The PR follows our CSS guide

[slaweet]

Thank you, Osvaldo 👍