Remove PreSizedInner{Input,Output}Stream

The classes PreSizedInnerInputStream and PreSizeInnerOutputStream are
not needed anymore due to changes from 5069fa5.
Use Int7 to prefix binary arrays and strings

The methods net.secloud.core.utils.BinaryReader and
net.secloud.core.utils.BinaryWriter now use the dynamic sized Int7 to
prefix the following length of arrays and string. This reduces space
consumption.
Compress blob content with GZip

Use library com.jcraft.jzlib to compress the binary content of a blob
with GZip before encrypting it.