- fix bashisms in post script

- Update to version 2.7.2:
For more see NEWS and UPGRADING in /usr/share/doc/packages/nut.
* upsdrvctl is now installed to $prefix/sbin rather than
$driverexec. This usually means moving from /bin to /sbin, apart
from few exceptions.
* FreeDesktop Hardware Abstraction Layer (HAL) support was removed.
* This is a good time to point out that for stricter packaging
systems, it may be beneficial to add "--enable-option-checking=fatal"
to the ./configure command line, in order to quickly pick up any
other removed option flags.
Other changes:
* libupsclient had undefined references related to functions of
libcommon.This issue was reported on Debian (bug #731156) and
is now fixed
* support for new devices:
+ CABAC UPS-1700DV2
+ Eaton Powerware 3105
+ Emerson Network Power Liebert PSI 1440
+ MicroDowell B.Box LP 500
+ Numeric Digital 800 plus
+ OptiUPS VS 575C
+ Tripp Lite SU10KRT3/1X
* nutdrv_atcl_usb: new driver for 'ATCL FOR UPS'
* al175: re-introduced this driver (actually, it was in 2.7.1)
* upsdrvctl now provides retry options for upsdrvctl and driver(s)
* snmp-ups: add support for XPPC-MIB and Tripp Lite SU10KRT3/1X.
Also fix erroneous status in HP/Compaq SNMP MIB (with the most
recent HP firmware (1.76) ;