Bug 920729 - Error after account creation ['logException is not defined' in mailInstrumentation.js] . r=standard8

Also fixes these:

Error: MailServices.accounts.defaultAccount.defaultIdentity is null
Source File: resource:///modules/mailInstrumentation.js
Line: 100

Error: this._removeObserver is not a function
Source File: resource:///modules/mailInstrumentation.js
Line: 61
Bug 302748 - HTML+plain-text (multipart) email message with wrong encoding does not upgrade to UTF-8 properly. r=irving

Characters outside current charset are converted into entities - should use utf-8 instead.