Two factor authentication support (#630)

* Initial commit for 2FA support

Signed-off-by: Andrew <write@imaginarycode.com>

* Add vendored files

* Add missing depends

* A few clean ups

* Added improvements, proper encryption

* Better encryption key

* Simplify "key" generation

* Make 2FA enrollment page more robust

* Fix typo

* Rename twofa/2FA to TwoFactor

* UNIQUE INDEX -> UNIQUE

vendor/github.com/boombuler/barcode/qr/unicode.go

@@ -0,0 +1,27 @@
+package qr
+
+import (
+	"errors"
+
+	"github.com/boombuler/barcode/utils"
+)
+
+func encodeUnicode(content string, ecl ErrorCorrectionLevel) (*utils.BitList, *versionInfo, error) {
+	data := []byte(content)
+
+	vi := findSmallestVersionInfo(ecl, byteMode, len(data)*8)
+	if vi == nil {
+		return nil, nil, errors.New("To much data to encode")
+	}
+
+	// It's not correct to add the unicode bytes to the result directly but most readers can't handle the
+	// required ECI header...
+	res := new(utils.BitList)
+	res.AddBits(int(byteMode), 4)
+	res.AddBits(len(content), vi.charCountBits(byteMode))
+	for _, b := range data {
+		res.AddByte(b)
+	}
+	addPaddingAndTerminator(res, vi)
+	return res, vi, nil
+}