Add -p/--profile flag to enable cpu/memory profiling

1. Compile the binary with the profiling flag in it.
2. Run the binary with profiling enabled: ./wtf -p
3. Run the go profiling tool against the resulting *.pprof file:

    go tool pprof --pdf /path/to/wtfbinary /var/path/to/cpu.pprof >
profile.pdf

4. View pretty PDF file

.gitignore

@@ -16,6 +16,8 @@
 .DS_Store
 gcal/client_secret.json
 gspreadsheets/client_secret.json
+profile.pdf
+
 #intellij idea
 .idea/