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/collation.go

@@ -0,0 +1,39 @@
+package mssql
+
+import (
+	"encoding/binary"
+	"io"
+)
+
+// http://msdn.microsoft.com/en-us/library/dd340437.aspx
+
+type collation struct {
+	lcidAndFlags uint32
+	sortId       uint8
+}
+
+func (c collation) getLcid() uint32 {
+	return c.lcidAndFlags & 0x000fffff
+}
+
+func (c collation) getFlags() uint32 {
+	return (c.lcidAndFlags & 0x0ff00000) >> 20
+}
+
+func (c collation) getVersion() uint32 {
+	return (c.lcidAndFlags & 0xf0000000) >> 28
+}
+
+func readCollation(r *tdsBuffer) (res collation) {
+	res.lcidAndFlags = r.uint32()
+	res.sortId = r.byte()
+	return
+}
+
+func writeCollation(w io.Writer, col collation) (err error) {
+	if err = binary.Write(w, binary.LittleEndian, col.lcidAndFlags); err != nil {
+		return
+	}
+	err = binary.Write(w, binary.LittleEndian, col.sortId)
+	return
+}