Add some currencies (see issue #4)

Add support for Scala 2.12

New Things

• Remove com.lambdista as a base package.
• Remove some counterintuitive operators.
• Provide a default implementation of Converter that can be used if one needs to work
  within one and just one currency.
• Refactoring.

New Things

• Simplify usage. Now only one import is needed.
• Remove logging config files that were no more used since 0.4.0.

New Things

• Remove logging.
• Bump to Scala 2.11.8 version
• Code cleanup

• Two Money objects, now, are equals iff they have the same amounts and currencies, no conversion is attempted if the currencies are different.
• Now you need to provide the conversion map in both ways, i.e. (USD, EUR) and (EUR, USD). Before this release if a conversion was not present the converter tried to find the opposite and provide (1 / value) as a conversion. For example, if there was the (USD, EUR) conversion and not the (EUR, USD) one then the converter returned (1 / x), where x = (USD, EUR) conversion rate. This behaviour has been removed because, this way, you have better precision. Of course, on the client side, one can decide to use the reciprocal (1 / x) trick.

• Add Numeric type class implementation
• Money, now, implements Ordered

Note that its version starts with 0 so anything may change at any time. The public API should not be considered stable. In this sense I'll strive to follow SemVer for versioning.