Renamed IpfixDbReaderMySQLCfg -> IpfixDbReaderCfg

First step towards a generic DB reader object
Removed IpfixDbReaderOracleCfg.{h,cpp}

Oracle DB Reader configuration should be performed by the common
configuration class for all DB Readers
Killed two options for DB reader

- timeshift
- fullspeed

The database reader configuration will now only be able to consume
flows in full speed with the time stamps used in the original database
flows.
Removed old MySQL DB reader from repository
Added new generic base for IPFIX Db Readers

Currently has mysql support only. Will be extended by the
next few commits.
Extended generic db reader / moved code to mysql

Re-Introduced MYQL reader for DB reading, which extends the
basic IpfixDbReader.
Ported Oracle DB Reader to new generic reader

The Oracle DB Reader now uses the generic reader classes and
can now read the new table format (similar than the MYSQL reader).
The code is not tested due to missing oracle libraries on the
development machine. Next commit should fix problems (if there are
any), and should probably be merged with this one ...)
Fixed oracle type lengths

uint8_t -> NUMBER(3)
utin16_t -> NUMBER(5)
uint32_t -> NUMBER(10)
uint64_t -> NUMBER(20)
IPFIX length 65535 -> VARCHAR(100) (dynamic length)