Added a .travis.yml file to allow Travis CI to perform build tests

.travis.yml

+language: cpp
+compiler:
+  - clang
+
+before_install:
+  - sudo apt-get update
+  - sudo apt-get install libpcre3 libpcre3-dev
+  - sudo apt-get install swig
+  - sudo apt-get install doxygen
+  - sudo apt-get install python-numpy
+  - sudo apt-get install python-scipy
+  
+script:
+  - cmake . && make && make test && sudo make install
+  - export LD_LIBRARY_PATH=/OpenMM/lib/
+  - export OPENMM_LIB_PATH=/OpenMM/lib/
+  - export OPENMM_INCLUDE_PATH=/OpenMM/include/
+  - cd python
+  - sudo -E python setup.py install
+  - cd tests
+  - python TestAmberPrmtopFile.py
+  - python TestDesmondDMSFile.py
+  - python TestForceField.py
+  - python TestGromacsTopFile.py
+  - python TestModeller.py
+  - python TestNumpyCompatibility.py
+  - python validateConstraints.py
+  - python validateConstraints.pyc
+  - python validateModeller.py