Aliases to digital sign/verify commits and tags (#651)

modules/git/alias.zsh

@@ -68,10 +68,11 @@ if ! zstyle -t ':prezto:module:git:alias' skip 'yes'; then
   alias gcr='git revert'
   alias gcR='git reset "HEAD^"'
   alias gcs='git show'
+  alias gpS='git show --pretty=short --show-signature'
   alias gcl='git-commit-lost'
   alias gcy='git cherry -v --abbrev'
   alias gcY='git cherry -v'
-
+  
   # Conflict (C)
   alias gCl='git --no-pager diff --name-only --diff-filter=U'
   alias gCa='git add $(gCl)'
@@ -190,6 +191,7 @@ if ! zstyle -t ':prezto:module:git:alias' skip 'yes'; then
   alias glg='git log --topo-order --all --graph --pretty=format:"${_git_log_oneline_format}"'
   alias glb='git log --topo-order --pretty=format:"${_git_log_brief_format}"'
   alias glc='git shortlog --summary --numbered'
+  alias glS='git log --show-signature'
 
   # Merge (m)
   alias gm='git merge'
@@ -255,6 +257,8 @@ if ! zstyle -t ':prezto:module:git:alias' skip 'yes'; then
   # Tag (t)
   alias gt='git tag'
   alias gtl='git tag -l'
+  alias gts='git tag -s'
+  alias gtv='git verify-tag'
 
   # Working Copy (w)
   alias gws='git status --ignore-submodules=${_git_status_ignore_submodules} --short'