Builtins (http.modules): Log levels and base64 dec/enc

Define more builtin functions in http.modules:
+ More log levels: log_deb, log_info, log_warn, log_error, log_fatal.
+ Add btoa/atob javascript functions.
Modify wiki to include this: https://github.com/bettercap/bettercap/wiki/http.modules

modules/base_proxy_script.go

@@ -3,6 +3,7 @@ package modules
 import (
 	"io/ioutil"
 	"sync"
+	"encoding/base64"
 
 	"github.com/bettercap/bettercap/log"
 	"github.com/bettercap/bettercap/session"
@@ -109,6 +110,69 @@ func (s *ProxyScript) defineBuiltins() error {
 		return otto.Value{}
 	})
 
+	// log debug
+	s.VM.Set("log_debug", func(call otto.FunctionCall) otto.Value {
+		for _, v := range call.ArgumentList {
+			log.Debug("%s", v.String())
+		}
+		return otto.Value{}
+	})
+
+	// log info
+	s.VM.Set("log_info", func(call otto.FunctionCall) otto.Value {
+		for _, v := range call.ArgumentList {
+			log.Info("%s", v.String())
+		}
+		return otto.Value{}
+	})
+
+	// log warning
+	s.VM.Set("log_warn", func(call otto.FunctionCall) otto.Value {
+		for _, v := range call.ArgumentList {
+			log.Warning("%s", v.String())
+		}
+		return otto.Value{}
+	})
+
+	// log error
+	s.VM.Set("log_error", func(call otto.FunctionCall) otto.Value {
+		for _, v := range call.ArgumentList {
+			log.Error("%s", v.String())
+		}
+		return otto.Value{}
+	})
+
+	// log fatal
+	s.VM.Set("log_fatal", func(call otto.FunctionCall) otto.Value {
+		for _, v := range call.ArgumentList {
+			log.Fatal("%s", v.String())
+		}
+		return otto.Value{}
+	})
+
+	// javascript btoa function
+	s.VM.Set("btoa", func(call otto.FunctionCall) otto.Value {
+		varValue := base64.StdEncoding.EncodeToString([]byte(call.Argument(0).String()))
+		v, err := s.VM.ToValue(varValue)
+		if err != nil {
+			return errOtto("Could not convert to string: %s", varValue)
+		}
+		return v
+	})
+
+	// javascript atob function
+	s.VM.Set("atob", func(call otto.FunctionCall) otto.Value {
+		varValue, err := base64.StdEncoding.DecodeString(call.Argument(0).String())
+		if err != nil {
+			return errOtto("Could not decode string: %s", call.Argument(0).String())
+		}
+		v, err := s.VM.ToValue(string(varValue))
+		if err != nil {
+			return errOtto("Could not convert to string: %s", varValue)
+		}
+		return v
+	})
+
 	// read or write environment variable
 	s.VM.Set("env", func(call otto.FunctionCall) otto.Value {
 		argv := call.ArgumentList