Simplify "basic installation" notes

[eric-hu]

Use the Rails-provided rake task for creating the dev database.

Change database-schema loading instructions, which is more future-proof. Running migrations on the latest build resulted in a schema.rb difference:

$ git status
On branch master
Your branch is up-to-date with 'origin/master'.
Changes not staged for commit:
  (use "git add <file>..." to update what will be committed)
  (use "git checkout -- <file>..." to discard changes in working directory)

  modified:   ../db/schema.rb

no changes added to commit (use "git add" and/or "git commit -a")
$ cd ..
$ git diff
diff --git a/db/schema.rb b/db/schema.rb
index 6c263e3..904a869 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -95,7 +95,6 @@ ActiveRecord::Schema.define(:version => 20131101180159) do
     t.datetime "created_at",                                :null => false
     t.datetime "updated_at",                                :null => false
     t.string   "handle"
-    t.boolean  "anonymous",              :default => false
     t.boolean  "guest",                  :default => false
     t.datetime "processing_timestamp"
     t.string   "access_token"

[dsjoerg]

Thank you! Looks good.

Good catch on the anonymous field. It's a mistake that the field was in schema.rb, I've removed it.