`html` and `text` templates for mailers by default
fix url connections for sqlite3
converts hashes in arrays of unfiltered params to unpermitted params [fixes #13382]
Merge pull request #13425 from kassio/master

Generates html and text templates for mailers by default.
Test with 2.1.0-rc1
refactors AC::Parameters#fetch

AC::Parameters#fetch was refactored in 7171111 to prevent self mutation, but
in doing so it hardcodes logic #convert_hashes_to_parameters is supposed to
encapsulate.

Better leave the delegation, and add a way to avoid mutating self in there.
Add a changelog entry for #13363 [ci skip]
optimizes array conversion in AC::Parameters
Add a changelog entry for #13326 [ci skip]
Fix typo [ci skip]
Fix few typos in the documentation [ci skip]
Enable memcached service on travis for running cache tests.
Merge pull request #13436 from robin850/patch-11

Add missing changelog entries and fix few typos
Merge pull request #13438 from vipulnsward/enable-memache-on-travis

Enable memcached service on travis for running cache tests.
Tell how to Create a Database in Error Message

Currently if you attempt to use a database that does not exist  you get an error:

```
PG::ConnectionBad FATAL:  database "db_error" does not exist
```

The solution is easy, create and migrate your database however new developers may not know these commands by memory. Instead of requiring the developer to search for a solution, tell them how to fix the problem in the error message:

```
ActiveRecord::NoDatabase: FATAL:  database "db_error" does not exist
Run `$ bin/rake db:create db:migrate` to create your database
```

Active Record should not know about `rake db:migrate` so this additional information needs to come from the railtie. Potential alternative implementation suggestions are welcome.