add option to avoid repmgrd started upon installation

Now repmgr.repmgrd.default has another option: REPMGRD_ENABLED. Valid
values are either yes or no.
fix: don't use Windows newlines
fix: check return values of freopen()

Some compiles complain about not checking the return value of freopen(),
so we check it
fixing more compiler warnings
fix: store the master connection user name on standby follow
Merge pull request #14 from wamonite/fix_follow_user

fix: store the master connection user name on standby follow
various improvements and bugfixes in the init script
Merge branch 'master' into REL2_0_STABLE