Update .gitignore

This patch updates .gitignore file to ignore potential build products,
tool object files and binaries

Also fixes issue ARM-software/tf-issues#35

Change-Id: I053dfba4ec8fecbcca081cad5b4bf94f8abfb15c

.gitignore

+# Ignore miscellaneous files
 cscope.*
+*.swp
+*.patch
+.project
+.cproject
+
+# Ignore build directory
+build/
+
+# Ignore build products from tools
+tools/**/*.o
+tools/fip_create/fip_create