Revert ".travis.yml: fail build when code in before_script or script blocks fails."

This reverts commit 0b3ec75.

We shouldn't use exit in .travis.yml as it exit immediately from a script
and don't allow to the Travis CI code to be executed at all. For
example, after_failure block won't be executed in this case.

Because errexit works as exit 1 we shouldn't use it too.

Addressed to #631

Author: php-coder

.travis.yml

@@ -9,7 +9,6 @@ env:
     - secure: "fBav56BzY+A+Vs1g9YSfo1oLDCO1rFrXl49lJkOA5/XpnsKEEs4lI2RcOzz0wiJKXFNgcliiAJWoYMI8Esqz+lkyFWan4ij5Co0UzJcytDuY+2o+jaqwx45DuDYPogABzT+hWjLCxQLLG46gUkChzT8kcvOOn6JxC7Ff8q5MnoM="
 
 before_script:
-  - set -o errexit # exit immediately when commands return a non-zero status
   - if [ "$SPRING_PROFILES_ACTIVE" = 'travis' ]; then
       mysql -u root -e 'CREATE DATABASE mystamps CHARACTER SET utf8;';
       mysql -u root -e "GRANT ALL PRIVILEGES ON mystamps.* TO 'travis'@'%';";
@@ -27,7 +26,6 @@ before_script:
     fi
 
 script:
-  - set -o errexit # exit immediately when commands return a non-zero status
   - if [ "$SPRING_PROFILES_ACTIVE" = 'travis' ]; then
       ./src/main/scripts/ci/check-build-and-verify.sh;
     else