Reformat en locale time formatting to fix issue for 12:00 AM formatting

[rokane]

Description:

This issue addresses a bug which was raised in #41 . Please see the issue comments for further understanding of the conversation around this issue.

TLDR:
According to the CLDR specification the 'en' locale should be formatting the value for 12:00 AM as 12:00 AM and not 00:00 AM

Changes:

• FmtTimeShort, FmtTimeMedium, FmtTimeLong and FmtTimeFull now displaying 12 for representing the hour 12:00 AM
• Unit tests added for each of the functions to cover this case.

Excluded:

In addition to this, I discovered the same issue exists for a large number of the en locales, any locale which should be formatting hours as the patter h as defined by the CLDR spec. I excluded these, due to a large number of unit tests being commented out for those locales. Given I am not aware of the context as to why they are commented out, I didn't want to touch those.

I have created a follow up issue to address this: #45

fixes #41

[rokane]

@deankarn I had a go at fixing this issue.
Can you please take a look and let me know what you think?