Deprecated API calls to be removed

[brodycj]

The following API calls are now deprecated and scheduled to be removed in the near future:

• "standard" transaction API calls (db.transaction() and db.readTransaction())
• Multi-part transactions (db.beginTransaction())

This is needed to support the Browser platform ref: storesafe/cordova-sqlite-evcore-extbuild-free#11 and avoid a number of other problems discussed in storesafe/cordova-sqlite-storage#690.

It is recommended to use the following calls instead:
To clarify: it is recommended to use the following calls in general:

• db.executeSql() to read data or execute a single statement
• db.sqlBatch() to execute a batch of modification statements within an ACID (atomic, failure-safe) transaction

NOTE that the db.sqlBatch() call is still not supported by this plugin version, will be added by merge in the near future ref: #4