Corrected the CQL output

`options.caching`'s value should be surrounded by quotes otherwise it
is not valid CQL, e.g.,
```
AND caching = 'KEYS_ONLY'
```
Corrected CQL generated for `CREATE INDEX`

Added a semicolon to `CREATE INDEX` statements.
put all host accesses in null guard
String.format not needed
Merge branch '1.0' into 2.0

Conflicts:
	driver-core/src/main/java/com/datastax/driver/core/Cluster.java
	driver-core/src/main/java/com/datastax/driver/core/ColumnMetadata.java