Make lifelines work in pure python mode

Added a pure python version of concordance index,
as a fallback option, for developers without access
to a proper compiler (Windows people). This allows for
easier contribution to the library, while still allowing
us to maintain the higher speed for users who install from
pypi.

The setup script will now try to compile the extensions, and if
it fails, it will do it again with just the python source.

Signed-off-by: Jonas Kalderstam <jonas@kalderstam.se>
Added test for python version of cindex

Signed-off-by: Jonas Kalderstam <jonas@kalderstam.se>
Improve equality test

Signed-off-by: Jonas Kalderstam <jonas@kalderstam.se>
Improve readability

Signed-off-by: Jonas Kalderstam <jonas@kalderstam.se>
Fix equality test

Signed-off-by: Jonas Kalderstam <jonas@kalderstam.se>
convert events variable to array. This fixes the failing test

Signed-off-by: Jonas Kalderstam <jonas@kalderstam.se>
Merge pull request #111 from CamDavidsonPilon/easier_dev

Make lifelines work in pure python mode