Allow user to set static page before saving

fixes #1350
- jQuery event.preventDefault() stops the user from selecting the checkbox
Pass proxy Ghost interface to Apps

Closes #1478

- Create new proxy.js that exposes createProxy method
- Pass proxy to App activate/install in lieu of Ghost instance
Fix wrong error message

closes #1466
- added status code for error object
- added test for frontend errors
Lowercase email address.

fixes #1498
Add schema.js

closes #1398
closes #1399
closes #1400
- added schema.js with database version '000'
- refactored migration to use schema.js
- if new table is added to schema.js and databaseVersion is increased, table will be added
- if new table is deleted to schema.js and databaseVersion is increased, table will be deleted
- alter table from issue #1400 is delayed until knex supports column modification
- changed import pre checks to work again (will be refactored separately)
- added basic PostgreSQL support (Attention: not supported/tested)
- changed error handling in server.js
Merge pull request #1489 from sebgie/issue#1466

Fix wrong error message
Merge pull request #1505 from halfdan/1498-lower-email

Lowercase email address.
Merge pull request #1353 from thgaskell/1350-static-page-checkbox

Allow user to set static page before saving
Correct the Markdown for emphasis
Merge pull request #1485 from Archanium/MinorIssues

Danish language file and a correction to Markdown modal
Merge pull request #1449 from sebgie/issue#1398

Add schema.js
Reduce size of ghost.js by moving related Routing code to their own files
Move server middleware configuration to related file
Set RSS link title to blog title
Add transactions for import

closes #837
- added transaction handling for import
- added transactions to model functions
- added simple tests for failing imports
Allow newline when quotes are used at start of a sentence

closes #974
Merge pull request #1482 from jgable/appProxy

Pass proxy Ghost interface to Apps
Merge pull request #1444 from hswolff/ghostjs-cleanup

Reduce size of server.js, moving code to their related files
Merge pull request #1531 from jamesbloomer/issue-974

Allow newline when quotes are used at start of a sentence
Merge pull request #1524 from jgillich/rss

Set RSS link title to blog title