work harder to avoid re-serializing headers

v0.4.31

version bump

Add != operator

Changes:

fix bug with != operator against a string (#78 @aroberts)

Thanks for the contribution!

Don't reserialize on header change, Reject consecutive dots in address

Changes:

• Don't re-serialize the whole message when headers ahve been prepended but nothing else has changed ( @jeremyschlatter)
• Reject consecutive dots (.) in gmail addresses (#89 @jessespears)

Hotmail address fix, Add to known domains list, Typo fix

Changes:

• Add yahoo.com.br to known domains list (#86 @lmcnearney)
• Allow hotmail addresses to begin with a number (#85 @lmcnearney)
• Typo fix (#81 @bulatb)

Thanks for the contributions!

v0.4.27: Merge pull request #76 from mailgun/rjones/content-type-override

Override tricky content types.

v0.4.26

Merged master.

v0.4.24: Merge pull request #71 from jeffwidman/patch-1

Fix two typos

v0.3.24: Merge branch 'master' into stable

Conflicts:
	setup.py

v0.4.23

Bump version.

v0.3.23

Bump version.