projectRootPath argument was added to installPods function and removed from iOSBuilderExecutor constructor, some refactoring was done

The only step which requires projectRoot to be specified is pods installing step. That's why we don't need that argument to be in the constructor.
Build-related exception stacktraces are now printed to the listener's logger – to simplify problems diagnosis.
EnvVars expanding was removed on some places as it's not mandatory to be there. For example, it's possible to remove them in build step command composing because all the envVars would be expanded during command executing.
Build directory path field has been placed above additional xcodebuild parameters field
Artifacts archiving was removed from the builder.

It's not builder's business to archive build artifacts as that could be done later in a post-build action.
Meanwhile it might be useful to specify a different path for an IPA archive and to zip dSYM folder. That's why two (in fact, three) new options were added.
In addition, zipping is possible using Jenkins' FilePath.zip method. That's why Zip class was removed from the plugin.
Code resigning was removed from the packaging step. Default IPA and dSYM zip names were changed.

It's almost useless to resign the IPA and, additionally, it's not possible to specify keychain during application packaging.
That's why it's more safe to remove resigning-related parameters from the packaging step.
One small change – the default name for ipa and dSYM's zip was changed from $APP_NAME to build/$APP_NAME – to place archives in the build folder.
Archive key ciphering was added.

hudson.util.Secret class is used to cipher the key. Seems like it's a common practice to use that class to secure passwords in Jenkins.
Archive key ciphering was added.

hudson.util.Secret class is used to cipher the key. Seems like it's a common practice to use that class to secure passwords in Jenkins.
Some refactoring was done.

Keychain lock timeout was removed (just in case, after it's unlocked, we execute `securoty set-keychain-settings -u $KEYCHAIN_NAME` to clear possible lock timeout).
launcher.launch()... calls were refactored. xcodebuildPath, securityPath etc. variables were renamed to xcodebuild, security etc. for better readability.
Some private variables were made final as they're supposed to be set in constructors.
Merge branch 'develop' of https://github.com/sharpland/iosbuilder-plugin into develop
Merge branch 'develop'