New matcher HasConsecutiveItems

When implementing a library to test compiler command-line arguments in the form:

  -x foo -y -z bar

I found I needed a Hamcrest matcher which would look for a consecutive
sequence of items anywhere inside a collection of items.

I was surprised that Hamcrest had matchers which:

1) Match if a collection includes a single item anywhere (`hasItem`)
2) Match if a collection includes multiple items anywhere (`hasItems`)
3) Match if a collection includes multiple items in order anywhere, consecutive or not (`containsInRelativeOrder`)
4) Match if a collection exactly matches another collection in order (`contains`)
5) Match if a collection exactly matches another collection in any order (`containsInAnyOrder`)

but not for a consecutive sequence of items anywhere inside the collection.

This implements such a matcher and adds tests. I borrowed the tests from `containsInRelativeOrder`,
so let me know if there are better tests I should include.
Fix openjdk6 build by removing @SafeVarargs
Rename HasConsecutiveItems to HasSubsequence
Merged PR #79 - New matcher HasSubsequence and changed code slightly to match "Hamcrest 7" style.
Generalised HasSubsequenceMatcher to be a matcher of Iterable, not Collection
Merge branch 'bgertzfield-has-consecutive-items' into v7.0