Force case insensitivity for new emails, existing.

There is a legacy bug I just caught, where many accounts would have the
same email but then have different casing. In extreme scenarios, this
would lead to them creating a new user with the same email, or having
issues with password reset and username lookup.

This doesn't merge in the existing duplicates, but makes sure to only
allow insensitive lowercase emails from here on out. It also will check
for emails in a case insensitive way for such things as resets and
logins if the sensitive lookup doesn't work.

The implementation was not wrong per se - email is supposed to be case sensitive
for usernames. But of course, nobody (nor do most/all email servers) treat
them that way, leading to confusion situations where the user sometimes
camelcases their email and then switches to lowercase later.

tests/acceptance/signin_tests.rb

@@ -60,6 +60,17 @@ describe 'signin' do
     page.must_have_content 'Your Feed'
   end
 
+  it 'signs in with invalid case username' do
+    pass = SecureRandom.hex
+    @site = Fabricate :site, password: pass
+    visit '/'
+    click_link 'Sign In'
+    fill_in 'username', with: @site.username.upcase
+    fill_in 'password', with: pass
+    click_button 'Sign In'
+    page.must_have_content 'Your Feed'
+  end
+
   it 'signs in with email' do
     pass = SecureRandom.hex
     @site = Fabricate :site, password: pass
@@ -70,4 +81,15 @@ describe 'signin' do
     click_button 'Sign In'
     page.must_have_content 'Your Feed'
   end
+
+  it 'signs in with invalid case email' do
+    pass = SecureRandom.hex
+    @site = Fabricate :site, password: pass
+    visit '/'
+    click_link 'Sign In'
+    fill_in 'username', with: @site.email.upcase
+    fill_in 'password', with: pass
+    click_button 'Sign In'
+    page.must_have_content 'Your Feed'
+  end
 end

tests/acceptance/signup_tests.rb

@@ -140,6 +140,20 @@ describe 'signup' do
     page.must_have_content /email.+exists/
   end
 
+  it 'fails with existing email even if case sensitive' do
+    email = Fabricate.attributes_for(:site)[:email]
+    fill_in_valid
+    fill_in 'email', with: email
+    click_signup_button
+    site_created?.must_equal true
+    Capybara.reset_sessions!
+    visit_signup
+    fill_in_valid
+    fill_in 'email', with: email.upcase
+    click_signup_button
+    page.must_have_content /email.+exists/
+  end
+
   it 'succeeds with no tags' do
     fill_in_valid
     fill_in 'new_tags_string', with: ''