update version to 1.2.5

fix the issue that `time.clock()` method no longer exists in higher v…

…ersion of python, and close #30

update comments of the coreset greedy and density weighted methods.

update version number

add long_description_content_type to setup.py

try to use another kernel to avoid DCPError

Merge branch 'master' of https://github.com/NUAA-AL/ALiPy

update version number

Merge branch 'dev'

Merge branch 'dev'

Update to v1.0.2