Version v0.2.5

• Let find_bin_index find indices for multiple x values (#199)
• Add get_bin_properties and change default: find_bin_index(use_kev=None) (#203)
• Issue tests #200: Spectrum tests and associated changes to bin-related methods and docstrings (#201)
• Update travis build spec, numba and llvmlite (#204)
• Update requirements to deal with python2/3 llvmlite issue (#205)