Remove USD references on UI

[kekkyojin]

PR Checklist

Please check all that apply to this PR using "x":

• I have checked that this PR is not a duplicate of an existing PR (open, closed or merged)
• I have checked that this PR does not introduce a breaking change

PR Type

What kind of change does this PR introduce?

• Bugfix
• Refactoring (no functional changes)
• Documentation changes

Fixes

Issue Number: #1

What is the current behavior?

Conversion from Credits to USD is displayed on some parts of the UI

What is the new behavior?

Conversion to USD is no longer displayed

Other information

This PR keeps code to retrieve the LBC/USD rate, as it could still be used, for example to convert the claim cost from USD to LBC -the dynamic pricing style-.

This PR is also removing a View which was acting as a separator. a layout marginTop attribute is used instead. This simplifies the layout processing.

[akinwale]

I would prefer to have this eventually be a setting that the user can toggle at a later date, so instead of removing the controls and the conversion methods, let's just set them as hidden / gone for now.

[akinwale]

Looks good.