Ease expected test failure.

In order to test Mocks i needed to ease failure verification.
For that purpose, I modified the output policy to bufferize every message until the end of each the test case.
So we can check that a test has failed with an expected message and then reset it to have a clean output.

This removes the output pollution and ease mock test coding.

`EXPECT_ABORT_BEGIN`, `VERIFY_FAILS_END` and `VERIFY_IGNORES_END` are now defined in unity.h.

`VERIFY_FAILS_END` is now `VERIFY_FAILS_END(expected_fail_message)`.
To be consistent `VERIFY_IGNORES_END` is now `VERIFY_IGNORES_END()`.

__note :__
Tests compilation makes gcc 4.9 to consume over 10G or RAM, a ticket has been [openned](https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=759683).