Allow overriding of SYSCONFDIR, LOCALSTATEDIR from recursor Makefile

Fixes #734.
add transaction-isolation=READ-COMMITTED to my.cnf in travis.yml
gpsqlbackend: don't append empty dbname=/user= values to connect string
gpsqlbackend: use empty defaults for dbname and user; libpq will use the current user name for both by default
add unit test to check if we detected byte order correctly
SUNWotis suggests using AF_UNIX over AF_LOCAL - http://stackoverflow.com/questions/6729366/what-is-the-difference-between-af-inet-and-pf-inet-in-socket-programming
output ZSK DNSKEY records if experimental-direct-dnskey support is enabled
Merge pull request #916 from mind04/dnskey

output ZSK DNSKEY records if experimental-direct-dnskey support is enabl...
Merge pull request #910 from stbuehler/gpgsql-backend-config

Gpgsql backend config
Merge pull request #908 from mind04/locking

add transaction-isolation=READ-COMMITTED to my.cnf
Merge pull request #881 from cmouse/config-incremental-support

Support for += syntax for options, candidate for ticket #502
Merge pull request #848 from zeha/f/issue-734

Allow overriding of SYSCONFDIR, LOCALSTATEDIR from recursor Makefile
fix recursor build due to CONFIGDIR/SYSCONFDIR change
Basic TSIG key management infrastructure
GSQL backend support for TSIG key management
GMySQL support for TSIG key management
Goracle backend implementation
Oraclebackend support for TSIG key management
SQLite3 support for TSIG key management
gpgsqlbackend support for TSIG key management