Add more assertion

[nohwnd]

changelog:

• Add -Because parameters to all assertions Fixes Add -Message param to Should assertion #312
• Add -BeLessOrEqual and -BeGreaterOrEqual
• Add -Contain (that operates on arrays) Fixes Should Contains for evaluating arrays #121
• Add -BeLikeExactly
• Add -HaveType alias to -BeOfType
• Fix assertion messages in -BeOfType Fixes BeOfType #729
• Throw argument exception when -BeOfType is given type that is not loaded
• Add -PassThru to -Throw to get the exception when some is thrown and passes the filters
• Add -BeTrue to test for truthy values
• Add -BeFalse to test for falsy values
• Add -HaveCount to count stuff in collections

Remove many duplicated tests in Be, and rewrite many tests using Verify to remove interdependencies between Shoulds