Add Travis CI's Build Matrix

See also : http://docs.travis-ci.com/user/build-configuration/#The-Build-Matrix
Add Travis build status badge

  NOTE : This URL indicate `dev`-branch status.
Merge pull request #4 from t-mat/travis-ci-build-matrix

Add Travis CI Build Matrix to decrease testing time
Travis status for both master & dev branches, thanks to Takayuki Matsuoka
Added : *_withDict to fullbench
changed naming convention to *_usingDict()
Add .gitattributes

See https://help.github.com/articles/dealing-with-line-endings for details.

This change is related to following issues :

    Issue 82:  Can't build lz4.c/h using Sun Studio 12 C compiler when lz4.c/h has Dos (Cr/LF) line endings
    http://code.google.com/p/lz4/issues/detail?id=82

    Issue 94:  Please use unix line ending
    http://code.google.com/p/lz4/issues/detail?id=94