Enables mssql support (#383)

* Enables mssql support

Port of dlobs work in gogs.
Enables options in index.js
Enables MSSQL as a database option in go.
Sets ID to 0 on initial migration. Required for
MSSQL insert statements.

Signed-off-by: Beau Trepp <beautrepp@gmail.com>

* Vendors in denisenkom/go-mssqldb

Includes golang.org/x/crypto/md4
as this is required by go-msssqldb

Signed-off-by: Beau Trepp <beautrepp@gmail.com>

vendor/github.com/denisenkom/go-mssqldb/error.go

@@ -0,0 +1,73 @@
+package mssql
+
+import (
+	"fmt"
+)
+
+// Error represents an SQL Server error. This
+// type includes methods for reading the contents
+// of the struct, which allows calling programs
+// to check for specific error conditions without
+// having to import this package directly.
+type Error struct {
+	Number     int32
+	State      uint8
+	Class      uint8
+	Message    string
+	ServerName string
+	ProcName   string
+	LineNo     int32
+}
+
+func (e Error) Error() string {
+	return "mssql: " + e.Message
+}
+
+// SQLErrorNumber returns the SQL Server error number.
+func (e Error) SQLErrorNumber() int32 {
+	return e.Number
+}
+
+func (e Error) SQLErrorState() uint8 {
+	return e.State
+}
+
+func (e Error) SQLErrorClass() uint8 {
+	return e.Class
+}
+
+func (e Error) SQLErrorMessage() string {
+	return e.Message
+}
+
+func (e Error) SQLErrorServerName() string {
+	return e.ServerName
+}
+
+func (e Error) SQLErrorProcName() string {
+	return e.ProcName
+}
+
+func (e Error) SQLErrorLineNo() int32 {
+	return e.LineNo
+}
+
+type StreamError struct {
+	Message string
+}
+
+func (e StreamError) Error() string {
+	return e.Message
+}
+
+func streamErrorf(format string, v ...interface{}) StreamError {
+	return StreamError{"Invalid TDS stream: " + fmt.Sprintf(format, v...)}
+}
+
+func badStreamPanic(err error) {
+	panic(err)
+}
+
+func badStreamPanicf(format string, v ...interface{}) {
+	panic(streamErrorf(format, v...))
+}