Allocate less things
Switch all #freeze changes to constants, namespacing them in Patterns
Renaming Patterns to Constants
Undoing the each_slice --> shift change; maybe not worth it
Addressing @jeremy's comments; this is beginning to look very nice
silence warning
remove default values from gemspec
Merge pull request #747 from zendesk/grosser/silence

silence warning
remove duplicate test
Merge pull request #681 from srawlins/allocate-less-things

Allocate less things

Conflicts:
	lib/mail/fields/common/common_field.rb
	lib/mail/utilities.rb
Merge pull request #748 from zendesk/grosser/gemspec

A grab bag of gemspec polish: removed superfluous defaults, switch to https url, simplify relative version.rb require
decode blank strings
Merge pull request #751 from zendesk/grosser/blank-q-value

Fix bug decoding empty strings
Support the null sender in the envelope from element class

Remove spurious check for envelope from address, since SMTP doesn't require it.
Added RFC 3464 to references directory
Fixed outdated stub that was sometimes breaking ci