Got rid of Optional boxes in failure messages.
New try without double wrapping of Optionals

* optionalWithStringRegExp was removed. So there is no textual stripping of Optional from the string representation
* Expression now takes and handles T?. So there is no wrapping of Optionals in the generic parameter of Expression
* expect takes a T?, because T is non-optional here and in Expression. So the case that we can put an optional into expect must be handled directly here.
* matchers handle the fact that the actual value is an optional were necessary.
Fix tests where the compiler fails to infer types.
Override beEmpty() to deal with ambiguity.

Alternatively, we could remove the NMBCollection variant and rely on
countElements/CollectionType.
This does not infer correctly in 6.1b3.
Correct the reference to inferencing in the readme.
Okay Xcode, whatever you say.
Merge pull request #42 from github/xcode-6.1b3-type-inferencing-correction

Fix tests where the compiler fails to infer types.
Updated Nimble to support Xcode 6.1 (for OS X)
Merge branch 'pr40'

Conflicts:
	Nimble/Matchers/BeEmpty.swift
Added travis-ci yaml file
Dropped to iOS 8.0 for travis-ci.
Gotcha, placeholder text
Added travis-ci build status to README