Added a new SQL parser for migrations.

This pull request adds a new option for the SQL script parser used during database migration.

This parser supports both SQL style line comments and comment blocks. SQL statements can span multiple lines but must be delimited with a semicolon. This allows for improved readability of SQL scripts.

The old parser expects one statement per line which may or may not end with a semicolon. This means the new parser can also process scripts written for the old parser if those scripts end each line with a semicolon.

For backwards compatibility reasons this parser isn't used unless the manifest contains a meta-data entry ```AA_SQL_PARSER``` with the value ```delimited```. If this value isn't specified or is set to ```legacy``` the old parser implementation is used.

**Example:**
Add the following entry to the AndroidManifest.xml:
```
        <meta-data
            android:name="AA_SQL_PARSER"
            android:value="delimited" 
```

It is now perfectly legal to write a migration script (e.g. 2.sql) that looks like this:
```
-- Create table for migration
CREATE TABLE Entity2
(
	Id INTEGER AUTO_INCREMENT PRIMARY KEY,
	Column TEXT NOT NULL,
	Column2 INTEGER NULL /* this column is new */
);

-- Migrate data
INSERT INTO Entity2
(
	Id,
	Column,
	Column2
)
SELECT	Id,
		Column,
		0 -- there's no such value in the old table
		FROM Entity;

-- Rename Entity2 to Entity
DROP TABLE Entity;
ALTER TABLE Entity2 RENAME TO Entity;
```

The same script, using the "legacy" parser, must look like this:
```
CREATE TABLE Entity2 (Id INTEGER AUTO_INCREMENT PRIMARY KEY, Column TEXT NOT NULL, Column2 INTEGER NULL);
INSERT INTO Entity2 (Id, Column, Column2) SELECT Id, Column, 0 FROM Entity;
DROP TABLE Entity;
ALTER TABLE Entity2 RENAME TO Entity;
```
Sure, its more compact but far less readable. Imagine doing the same with a table containing 20 or more columns... :)