template fixes

src/Core/MailTemplates/ChangeEmail.text.cshtml

@@ -1,6 +1,6 @@
 @model Bit.Core.Models.Mail.ChangeEmailViewModel
 @{
-    Layout = "_BasicMailLayout";
+    Layout = "_BasicMailLayout.text";
 }
 To finalize changing your email address enter the
 following code in the pop-up window: @Model.Token

src/Core/MailTemplates/ChangeEmailAlreadyExists.text.cshtml

@@ -1,6 +1,6 @@
 @model Bit.Core.Models.Mail.ChangeEmailExistsViewModel
 @{
-    Layout = "_BasicMailLayout";
+    Layout = "_BasicMailLayout.text";
 }
 A user ({{fromEmail}}) recently tried to
 change their account to use this email

src/Core/MailTemplates/NoMasterPasswordHint.text.cshtml

@@ -1,6 +1,6 @@
 @model Bit.Core.Models.Mail.BaseMailModel
 @{
-    Layout = "_BasicMailLayout";
+    Layout = "_BasicMailLayout.text";
 }
 You (or someone) recently requested your
 master password hint. Unfortunately, your

src/Core/MailTemplates/Welcome.cshtml

@@ -1,6 +1,6 @@
 @model Bit.Core.Models.Mail.BaseMailModel
 @{
-    Layout = "_BasicMailLayout";
+    Layout = "_MailLayout";
 }
 <table class="main" width="100%" cellpadding="0" cellspacing="0" style="-webkit-font-smoothing: antialiased; -webkit-text-size-adjust: none; border: 1px solid #e9e9e9; border-radius: 3px; box-sizing: border-box; color: #333; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; font-size: 16px; line-height: 25px; margin: 0;" bgcolor="white">
     <tr style="-webkit-font-smoothing: antialiased; -webkit-text-size-adjust: none; box-sizing: border-box; color: #333; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; font-size: 16px; line-height: 25px; margin: 0;">

src/Core/MailTemplates/Welcome.text.cshtml

@@ -1,6 +1,6 @@
 @model Bit.Core.Models.Mail.BaseMailModel
 @{
-    Layout = "_BasicMailLayout";
+    Layout = "_MailLayout.text";
 }
 Thank you for creating an account with bitwarden.
 You may now log in with your new account.

src/Core/Services/Implementations/RazorViewMailService.cs

@@ -139,7 +139,15 @@ namespace Bit.Core.Services
 
         public async Task SendWelcomeEmailAsync(User user)
         {
-            throw new NotImplementedException();
+            var message = CreateDefaultMessage("Welcome", user.Email);
+            var model = new BaseMailModel
+            {
+                WebVaultUrl = _globalSettings.BaseVaultUri,
+                SiteName = _globalSettings.SiteName
+            };
+            message.HtmlContent = _engine.Parse("Welcome", model);
+            message.TextContent = _engine.Parse("Welcome.text", model);
+            await _mailDeliveryService.SendEmailAsync(message);
         }
 
         private MailMessage CreateDefaultMessage(string subject, string toEmail)