add configuration for mailcatcher

3 jobs for master in 2 minutes and 44 seconds (queued for 2 seconds)
Name Stage Failure
failed
build56 Build
  libgnutls-openssl27
The following NEW packages will be installed:
libgnutls-openssl27 ssmtp
0 upgraded, 2 newly installed, 0 to remove and 7 not upgraded.
Need to get 239 kB of archives.
After this operation, 236 kB of additional disk space will be used.
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The command '/bin/sh -c apt-get install ssmtp && echo "mailhub=mailcatcher:1025\nUseTLS=NO\nFromLineOverride=YES" > /etc/ssmtp/ssmtp.conf && echo "sendmail_path = /usr/sbin/ssmtp -t" > /usr/local/etc/php/conf.d/sendmail.ini' returned a non-zero code: 1
ERROR: Job failed: command terminated with exit code 1
failed
build72 Build
 ---> 519cc8e0781d
Step 7/11 : RUN apt-get install ssmtp && echo "mailhub=mailcatcher:1025\nUseTLS=NO\nFromLineOverride=YES" > /etc/ssmtp/ssmtp.conf && echo "sendmail_path = /usr/sbin/ssmtp -t" > /usr/local/etc/php/conf.d/sendmail.ini
---> Running in 2c5b0054e978
Reading package lists...
Building dependency tree...
Reading state information...
E: Unable to locate package ssmtp
The command '/bin/sh -c apt-get install ssmtp && echo "mailhub=mailcatcher:1025\nUseTLS=NO\nFromLineOverride=YES" > /etc/ssmtp/ssmtp.conf && echo "sendmail_path = /usr/sbin/ssmtp -t" > /usr/local/etc/php/conf.d/sendmail.ini' returned a non-zero code: 100
ERROR: Job failed: command terminated with exit code 100
failed
build71 Build
 ---> 2b4fd2ffd5bf
Step 7/11 : RUN apt-get install ssmtp && echo "mailhub=mailcatcher:1025\nUseTLS=NO\nFromLineOverride=YES" > /etc/ssmtp/ssmtp.conf && echo "sendmail_path = /usr/sbin/ssmtp -t" > /usr/local/etc/php/conf.d/sendmail.ini
---> Running in 600bfe52b300
Reading package lists...
Building dependency tree...
Reading state information...
E: Unable to locate package ssmtp
The command '/bin/sh -c apt-get install ssmtp && echo "mailhub=mailcatcher:1025\nUseTLS=NO\nFromLineOverride=YES" > /etc/ssmtp/ssmtp.conf && echo "sendmail_path = /usr/sbin/ssmtp -t" > /usr/local/etc/php/conf.d/sendmail.ini' returned a non-zero code: 100
ERROR: Job failed: command terminated with exit code 100