Tweaking on datetime parsing

[mokaddem]

• check for timezone sign after the date field
• updated *-seen test to avoid errors while testing using python 3.6 (do not support tz=08:00 but do support 0800)

[coveralls]

Coverage increased (+0.03%) to 37.631% when pulling 5277476 on datetime-parsing into 3dddacc on master.

[coveralls]

Coverage increased (+0.03%) to 37.631% when pulling 5277476 on datetime-parsing into 3dddacc on master.

[codecov]

Codecov Report

Merging #534 into master will increase coverage by 0.02%.
The diff coverage is 50%.

@@            Coverage Diff             @@
##           master     #534      +/-   ##
==========================================
+ Coverage   37.66%   37.69%   +0.02%     
==========================================
  Files          35       35              
  Lines        7064     7064              
==========================================
+ Hits         2661     2663       +2     
+ Misses       4403     4401       -2

Impacted Files	Coverage Δ
tests/testlive_comprehensive.py	0% <0%> (ø)	⬆️
pymisp/mispevent.py	69.68% <100%> (+0.18%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 3dddacc...5277476. Read the comment docs.