Adds a new package for parsing v1 and v2 M-Lab hostnames

[nkinkade]

As we transition to v2 names, we need for other Go programs to not have to worry about which version a name is, but simply get what it needs from the name. Currently, we have multiple Go programs that perform their own regexps on hostnames to parse them. Rather than having to rewrite the same regexps all over the place, these programs should be able to use this package instead.

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This change is 

[coveralls]

Pull Request Test Coverage Report for Build 800

• 37 of 37 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.4%) to 81.574%

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Totals
Change from base Build 791:	0.4%
Covered Lines:	1368
Relevant Lines:	1677

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💛 - Coveralls