Optional hour:minute, second and timezone in TimeValue

[thiemowmde]

This restores the behavior of the old regex in https://github.com/wmde/DataValuesJavascript/blob/0.6.1/lib/time/time.Time.js#L259:

• The trailing "Z" is optional.
• Second is optional.
• Hour:minute is optional.
• Hour, minute and second can have any number of digits, similar to day and month.

Note that actual validation should not be done here but server-side instead. Therefor it's ok to have a very relaxed regex here.

Bug: T89243

[thiemowmde]

I added tests. I would love to have this merged before making a new release because this restores behavior that got removed in #61. @adrianheine?

[thiemowmde]

I refuse to make the code worse and less readable because of an obtrusive tool with rules that neither indicate errors nor increase readability.

PS: Feel free to add a commit and revert my change in .jshintrc if you care.