Make all paths from glob be realpaths.

This is an attempt to fix the issue with AIX's glob results as discussed in https://github.com/composer/composer/pull/1812#issuecomment-41171660

Unit tests pass with 1 skip

There was 1 skipped test:

1) Composer\Test\Package\Archiver\ArchivableFilesFinderTest::testHgExcludes
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