Update commands.rb content in initialization guide

[ci skip]
Add section for command_tasks in initialization guide

[ci skip]
Extract common database defaults; better use of YAML
Merge pull request #12292 from bf4/better_database_yaml

Extract common database defaults; better use of YAML
Merge pull request #12803 from arunagw/remove-unused-require

Removed unused require
Merge pull request #12609 from corwinkelly/patch-1

Update workaround for "Outside the Scope of Strong Parameters"
removes redundant curly brackets in example code [ci skip]
Don't skip tests if we don't need to.

We can conditional define the tests depending on the adapter or
connection.

Lets keep the skip for fail tests that need to be fixed.
fix simple_format escapes own output when sanitize is set to true
Remove more skip
Mark broken test as pending

This will avoid the broken window effect in our test suite
:scissors: fix broken url [ci skip]
Start Running tests on Stable JRuby

Fixes for LOT of bugs have now landed in Jruby 1.7.6, thus we no longer
need to run tests against the master.

for broken tests that are still remaning:
1. If problem is in rails - we fix that test/code
2. if its a JRuby bug - we skip that test & file a bug report for jruby.
Merge pull request #12814 from gaurish/enable-jruby19-again

Start Running tests on Stable JRuby
Merge pull request #12813 from gaurish/patch-2

fix broken url/formatting in Asset pipeline guide [ci skip]
Update security.md

Hi Guys 
I was reading through this guide last night and noticed a small mistake, would be great if you could update it. 
I changed the word 'building' to 'build' in line 20. 
"Web application frameworks are made to help developers building web applications"
Skip test which is broken on jruby

This test is broken from quite a while & is expected to remain broken as
encoding issues are hardest to fix in JRuby. so lets skip this test for
now
Extract common code from number helpers to new delegator method.
Merge pull request #12806 from vipulnsward/extract_common_code_in_number_helper

Extract common code from number helpers to new delegator method.
Merge pull request #12816 from gaurish/skip-static-test

Skip test which is broken on jruby