Provide boolean object to compute

Summary:
The Boolean objet allows to represent a boolean and perform logical operations.

Allow to apply the main logical operations:

• and()
• or()
• not()

Allow to apply logical secondary operations:

• xor()
• implication()
• equivalence()

Allow to convert to other scalar types:

• asBool()
• asInteger() when you need 0 or 1
• asString() for debug representation

*Use case*

The main motivation is $result &= $callback() uses the bitwise operator &
and as such will return 0 or 1 instead of true and false.

With Boolean, $result.and($callback()) will work as expected.

Test Plan:
Unit tests provided

Equivalence tables have been checked against the English Wikipedia
article Boolean algebra.

Reviewers: dereckson

Reviewed By: dereckson

Differential Revision: https://devcentral.nasqueron.org/D3222